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Sunday, September 16, 2018

Pipeline Abandonment

  Tiffini       September 16, 2018       guideline , offshore , onshore , pipeline , procedure       No comments    

 

Requirements

Pipelines should be decommissioned and abandoned (by removal or abandonment-in-place) in accordance with applicable national, regional and local regulations and requirements, concession terms and contractual agreements, and permit requirements. In the case of conflict the more stringent requirement should apply, unless an exception procedure is implemented to approve and document the deviation. Pipelines should be abandoned using generally accepted engineering and construction practices, proven industry processes, methods and procedures, as well as with due consideration for health, the environment and safety, sustainability and reuse, and Company reputation, both during abandonment activities and considering future land or sea use.

  1. All onshore pipelines on the surface, and in depths shallower than 200 feet (below mean sea level) should be removed, unless buried to an acceptable depth below the surface or seabed suitable for abandonment-in-place. If abandoned in place, pipeline stability should be assured over the long term.
  2. If a pipeline (or group of similar pipelines) is a candidate to be abandoned-in-place, a risk assessment should be performed in the early phase of abandonment planning to determine whether the pipeline should be removed or abandoned-in-place. The risk assessment should be consistent with the HSE risk management process and evaluate HSE, business, social, and reputational risk. The risk assessment should evaluate relevant criteria (such as potential public exposure, future land or sea uses, e.g. fishing or shipping, regulatory requirements, rights-of-way, landowner agreements, and technical feasibility) and the results documented and considered in making the removal versus abandonment-in-place decision. If abandonment-in-place is selected, appropriate mitigations should be implemented based on the risk assessment results.
  3. A pipeline should not be removed or abandoned in place without first being cleaned to an acceptable standard, which is normally achieved by pigging and then flushing or purging the pipeline of hazardous liquids and gases, including hydrocarbons or other materials. Materials flushed or purged from liquid pipelines must be captured and sent for proper reuse or disposal. Gaseous materials may be permitted to be vented to atmosphere or to a control device if not purged to an active pipeline segment or otherwise captured for reuse. Regulatory approvals and permits may be required for the venting of gaseous materials or routing to a control device. The HSE department should be consulted for guidance on acceptable criteria and requirements for disposal or discharge of liquids and gases.
  4. An unidentified pipeline should not be cut, sheared, drilled or welded upon. If unsure, check all related documentation (e.g. drawings, surveys, maps, regulatory records), interview operations staff (current and previous) and discuss with other operators that have pipelines in the vicinity to positively identify the pipeline in question. If questions persist, perform additional surveys and trace the line to its source (e.g. with sonar or divers) to positively identify the pipeline.
  5. Hazardous wastes should be properly disposed of at an approved hazardous waste facility. Decommissioned materials containing hazardous wastes should either be sent to a decontamination facility (where the hazardous wastes should be removed and properly disposed of at an approved hazardous waste facility) or disposed of at an approved hazardous waste facility.
  6. Environmental site assessment, remediation, and restoration should be coordinated with the pipeline abandonment work. Environmental Subject Matter Experts should be engaged during project planning and execution phases to determine if environmental assessment, remediation, and/or restoration activities are required. Onshore, coastal and offshore areas (land or seabed surfaces) should be left in a state suitable for subsequent use, without being a hazard to users of the areas.
  7. Pipeline abandonment projects should define minimum technical capability and experience expectations within contract plans and bid/tender packages as needed to assure workforce competency for work execution.
  8. Items to consider in early-phase project framing and alternative development include pipeline abandonment-in-place versus removal, timing of work activities, regulatory requirements, HSE issues and risks, financial issues and risks, disposal requirements, and stakeholder requirements or expectations. Each region where Company operates may have unique requirements, and the abandonment plan must be suited to the overall goals of both Company and external stakeholders.
  9. Site visits and inspections should be undertaken during the planning and engineering phases to build an understanding of the site and establish detailed site-specific information, to identify issues that may need to be addressed in site-specific abandonment procedures or incorporated into analytical models, and to develop detailed abandonment execution plans and removal procedures.
  10. The site visit and inspection should include assessment of the condition of the pipeline, associated facilities and infrastructure, and site conditions. The visit should include inspection, testing and documentation of the presence of hazardous materials. Typical materials that might be encountered at pipelines and associated facilities (which may or may not be hazardous) include the following:
  • Naturally occurring radioactive material (NORM)
  • Asbestos
  • H2S
  • Mercury
  • Paint and lead-based paint
  • Batteries
  • Hydrocarbons
  • Polychlorinated biphenyls (PCBs)
  • Chemicals of unknown composition
  • Containers of unknown material
  1. A basis of estimate document should be developed for each pipeline abandonment project to guide the development of cost estimates. Where possible, individual pipeline abandonment projects may be grouped to form a campaign and thereby provide more leverage in dealing with contractors for securing equipment and reducing costs, and in gaining efficiencies through process repetition.
  2. The following items should be considered and incorporated as appropriate during early phase project development and planning.
  • Regulatory requirements governing pipeline abandonment vary by country, and even within various regulatory jurisdictions within a country. Therefore national, regional and local regulations, concession terms and contractual agreements, and permit requirements should be reviewed, as well as government decrees in place at the time of project development and planning, including those that define hazardous wastes and hazardous waste management requirements. Permits are generally required where a regulatory framework exists, and some permitting processes may require a public comment period.
  • A Transportation and Waste Management Plan should be developed that covers the handling, storage, transport and disposal of all wastes, including the recycling of scrap materials and the disposal of wastes, both hazardous and nonhazardous materials.
  • Pipeline abandonment risks should be assessed using the HSE Risk Management process to evaluate HSE, business, social, and reputational risk. Risk registers that include HSE, project execution and Company reputational risk factors should be developed and appropriate risk mitigation plans developed and managed. Assets with similar HSE, reputational, and project execution risks may be grouped together to facilitate assessment.

Onshore Pipeline Abandonment

All onshore pipelines should be removed unless buried to a minimum of 3 feet below the surface, in which case abandonment-in-place may be an alternative. Where national, regional or local regulations and requirements, concession terms and contractual agreements, or permit requirements allow abandonment-in-place at depths shallower than 3 feet, a risk assessment should be performed to confirm that abandonment-in-place is sufficiently protective of the Company’s interests from all perspectives, including HSE, business, social, and reputation. If the risk assessment confirms that abandonment-in-place is sufficiently protective of the Company’s interests then an exception procedure is not required. For onshore facilities, minor equipment, piping and appurtenances (and subsurface infrastructure) associated solely with pipeline operation and safety may be decommissioned and removed with the pipeline.

  1. Plan the pipeline abandonment, including isolation, draining, pigging, flushing, contents disposal, removal versus abandonment-in-place, and reclamation and restoration of impacted areas. Perform site visits, surveys, content-sampling, survey-map reviews, etc., as needed, as well as identifying in-line valves, repair locations, pipeline crossings, dead legs or other features that may require mitigation procedures.
  2. Pipeline right-of-way agreements should be reviewed for special requirements, and to verify that the agreement will not be violated or that Company rights will not be unintentionally relinquished.
  3. Sample the pipeline to determine the contents, then check contents for hazardous chemicals, materials or wastes (e.g., NORM, mercury or benzene) and check external coatings such as paint and insulation for potentially hazardous wastes (e.g., lead, asbestos, PCBs) that might require special handling procedures, disposal permits, or both.
  4. De-energize and isolate the pipeline from energy sources. Where a pipeline to be abandoned is connected to other pipelines (or segments) that are to remain active (live), inactive or idle, the abandoned pipeline should be isolated by physical removal, e.g., “air-gapped.” All abandoned connections to active, inactive or idle pipelines should be permanently closed with flanges and blinds (or weld caps) per the pipeline material classification or specification. All welds and flanged joints installed to achieve isolation should be inspected and tested per the pipeline material classification or specification. Lock out and tag out all sources of energy (e.g., pumps, rectifiers, cathodic protection systems, and valves) that are not physically disconnected.
  5. Drain pipeline and dispose of the contents per the Company’s waste management plan. For pipelines with unknown or uncertain integrity, perform a negative pressure test (normally 10–15 psi for 12 hours) to verify pipeline integrity for subsequent pigging and flushing operations.
  6. Pipelines with suitable integrity (or with a successful negative pressure test) should be pigged and flushed to remove as much of the remaining contents as possible. For pipelines with uncertain integrity, consider using negative pressure to pull a pig thru the pipeline to remove fluids, which mitigates the risk of releasing contents to the environment. Recover all fluids and dispose of as per the waste management plan.
  7. Flush or purge the pipeline to the cleanliness level specified by national, regional and local regulations and requirements, concession terms and contractual agreements, or permit requirements. If unspecified by regulations or contractual agreement, project team should set the minimum cleanliness level, which for example may be specified in parts per million or “flushing until clear returns”, e.g., until there is no sheen on receiving waters in a static sheen test. The minimum cleanliness requirement should be flushing until clear returns if no other requirements have been established. The minimum pipeline flushing volume to achieve clear returns should be 150% of the pipeline volume, but flushing efficiency is also dependent upon achieving adequate flow velocity, so higher volumes/flowrates may be required.
  8. Drain the pipeline to remove, recover and dispose of flushing fluids per the waste management plan. Re-pigging the pipeline with an inert gas (typically nitrogen) is one method to remove flushing fluids.
  9. Prior to severing or cutting a pipeline, verify the pipeline is depressurized and free of hazardous liquids and gases, including hydrocarbons.
  10. Pipelines (or segments) that are abandoned in place should meet the following requirements:
  • Each end of the pipeline should remain buried to a minimum depth of 3 feet or greater. Measures should be taken to ensure the pipeline ends remain stable and do not experience excessive settlement or buoyant movements during seasonal changes in soil conditions.
  • Each end of the pipeline should be sealed with a welded cap, a steel plate, a skillet plate, a blind flange, a locking plug, or a grout plug.
  • Each end of the pipeline should be permanently identified and then covered with appropriate materials.
  • Grouting of pipelines should be required where loss of integrity (e.g. collapse of the pipe, holes, buoyancy) could potentially result in an unacceptable risk or liability to the Company (e.g. pipe greater than 10 inches in diameter under roads or railroads, under canals, dikes, sea defense or dune crossings where the water level is higher than the surrounding land surface, or where local regulations require continuous plugging). Grouting should form a continuous plug throughout the pipeline (or section of pipeline) to mitigate the risk to an acceptable level.
  • Pipelines should be marked with above-ground pipeline warning markers if required by applicable national, regional or local regulations and requirements, concession terms and contractual agreements, or rights-of-way or permit requirements.
  1. Pipelines (or segments) that are removed should meet the following requirements:
  • Pipelines on the surface should be removed by severing in place and removal.
  • Pipelines buried shallower than 3 feet in depth should require excavation, severing and removal. Excavation should follow established safety procedures and may require special permits.
  • Cold-cutting methods are preferred (e.g., shearing, reciprocating or circular metal saws) over hot work methods from a safety perspective. All work should follow applicable safety procedures.
  1. Remove all associated pipeline surface and subsurface infrastructure (including at coastal sites) unless they have future economic utility.
  2. Remove all pipeline minor equipment, piping and appurtenances associated solely with pipeline operation and safety, unless they have future economic utility.
  3. Associated pipeline infrastructure such as buildings, roads, power lines, gravel pads, and concrete pads should be removed unless regulations, government requirements, concession or landowner/lease agreements stipulate that they remain in place.
  4. Document final site condition and retain all records (including, for example, “as abandoned” drawings, before-and-after photos or videos, regulatory submittals, permits and approvals, contractual records, route maps and end points of abandoned-in-place pipelines, sampling reports, and inventory data).

Offshore Pipeline Abandonment

All offshore pipelines in water depths shallower than 200 feet below mean sea level should be removed, unless buried to a minimum of 3 feet below the seabed surface, e.g. below the natural seafloor, in which case abandonment-in-place may be an alternative.

Reburial to the 3 feet minimum below the seabed surface may also be an acceptable alternative to removal. Buried pipelines in water depths from 200 feet to 300 feet are candidates for abandonment-in-place regardless of burial depth, provided that they do not present a hazard (obstruction) to navigation, commercial fishing (trawling) activities or future use. Where national, regional or local regulations and requirements, concession terms and contractual agreements, or permit requirements allow abandonment-in-place at depths shallower than 3 feet a risk assessment should be performed to confirm that abandonment-in-place is sufficiently protective of the Company’s interests from all perspectives, including HSE, business, social, and reputation. If the risk assessment confirms that abandonment-in-place is sufficiently protective of the Company’s then an exception procedure is not required.

  1. Plan the pipeline abandonment, including isolation, contents disposal, removal versus abandonment-in-place, and impacted areas. Perform site visits, surveys, contents sampling, survey map reviews, etc., as needed, as well as identifying in-line valves, repair locations, anchors, anchor mats, pipeline crossings, power or communications cable crossings, dead legs or other features that may require mitigation procedures. During the site visit, meet with field engineers and operators to discuss the history and condition of the pipeline (e.g., last time pigged, paraffin plugs, corrosion issues, repair details, and number of repairs) and identify potential concerns such as areas of high scour, sea bottom mudslides, and environmentally sensitive areas.
  2. Pipeline agreements (e.g. right-of-way, crossing, access to third party facilities, fluid handling) should be reviewed for special requirements, and to verify that the agreement will not be violated or that Company rights will not be unintentionally relinquished. Particular attention should be given to retaining rights-of-way at shore crossings where future use is of concern.
  3. Where seabed or environmental conditions (e.g., mud flows, erosion, currents, storms, mudslides, sediment movement, seismic events) may have caused a pipeline to move or shift, consider surveying affected pipelines with sonar equipment or by diver with a GPS pinger. The intent is to verify the line location, identify damage and locate impediments to abandonment (e.g., pipeline crossings, electrical power or communications cable crossings, valves, repair clamps, auger anchors, and concrete mats), and to determine the type and location of debris (shipwrecks, containers, etc.) on or near the pipeline. This information will be critical for planning pipeline abandonment.
  4. Sample the pipeline to determine the contents, then check contents for hazardous chemicals, materials or wastes (e.g., NORM, mercury or benzene) and check external coatings such as paint and insulation for potentially hazardous wastes (e.g., lead, asbestos, PCBs) that might require special handling procedures, disposal permits, or both.
  5. De-energize and isolate the pipeline from energy sources. Where a pipeline to be abandoned is connected to other pipelines (or segments) that are to remain active (live), inactive or idle, the abandoned pipeline should be isolated by physical removal, e.g. “water gapped” or “air gapped”. All abandoned connections to active, inactive or idle pipelines should be permanently closed with flanges and blinds (or weld caps) per the pipeline material classification or specification. All welds and flanged joints installed to achieve isolation should be inspected and tested per the pipeline material classification or specification. Lock out and tag-out all sources of energy (such as pumps, rectifiers, cathodic protection systems, and valves) that are not physically disconnected.
  6. If possible, pig the pipeline to be abandoned. Recover all fluids and dispose of them in accordance with the waste management plan, taking into account waste characteristics.
  7. Flush or purge the pipeline to the cleanliness level specified by national, regional and local regulations and requirements, concession terms and contractual agreements, and permit requirements. If unspecified by regulations or contractual agreement, the project team and management should set the minimum cleanliness level, which for example may be specified in parts per million or “flushing until clear returns”, e.g., until there is no sheen on receiving waters in a static sheen test. The minimum cleanliness requirement should be flushing until clear returns if no other requirements have been established. The minimum pipeline flushing volume to achieve clear returns should be 150% of the pipeline volume, but flushing efficiency is also dependent upon achieving adequate flow velocity, so higher volumes/flowrates may be required.
  8. Pipelines should not be cut, severed, sheared, drilled or welded upon unless it can be positively identified along its entire length (with no risk of misidentification) and there is a reasonable assurance that it has been flushed, depressurized to an equilibrium state, and is free of hazardous liquids and gases, including hydrocarbons. Suitable safeguards should be employed to mitigate risk (i.e., drilling a pilot hole and checking contents, setting a pollution dome, etc.) and to protect against releasing hazardous materials to the environment.
  9. Where there is any doubt or question relative to the identity, depressurization or cleanliness of a pipeline, and the decision has been made to proceed with cutting, severing, shearing, drilling or welding, suitable precautions should be taken to mitigate the higher risk. One proven industry practice is to use “hot tap” methods to verify that the pipeline is depressurized, and to confirm that the pipeline has been flushed and cleaned, and the contents are suitable for release to the environment. The “hot tap” provides a means of controlling flow and sampling/testing the contents, and if the contents are not clean it provides a means of localized flushing to further clean the line. The “hot tap” provides pressure and flow control mitigation against cutting into the wrong pipeline, which could be pressurized with hazardous contents.
  10. Whether severed in place for removal or abandonment-in-place, precautions should be instituted to protect divers, surface personnel, equipment and marine vessels, and the environment during subsea work. Containment domes (hoods) are one mitigation method against inadvertent fluid releases during subsea severing of pipelines.
  11. On conventional fixed structures the pipeline and tube turn are often severed and removed together, and the riser left in place for removal with the jacket as part of facility decommissioning. In this case the pipeline riser should be severed inside the jacket footprint, and sufficiently supported by the jacket to allow safe lifting with the jacket. A plug should not be placed in the bottom of a riser as it can present a projectile hazard during jacket lifting and removal.
  12. Abandoned pipeline segments, and related appurtenances such as risers, equipment, and piping that are cleaned and abandoned, but not removed should be identified as such with nameplate tags. The tags should include the pipeline number (or segment number), with date abandoned, and facility “to/from” information. Nameplate tags are typically fabricated from brass (other materials may be acceptable) and should be attached with nylon tie-wraps if subsea, and with stainless steel wire if on surface facilities.
  13. Pipelines (or segments) that are abandoned in place in water depths of 300 feet or less should meet the following requirements unless noted otherwise:
  • Each end of the pipeline should be buried to a depth of 3 feet or greater. In areas with evidence of seabed scour, additional precautions should be taken to mitigate erosion resulting from abandonment activities.
  • Each end of the pipeline should be sealed with a blind flange or a locking plug regardless of water depth, i.e., even in water depths greater than 300 feet. Examples of suitable locking plugs include a “dogging type internal plug” on pipelines 6 inches and larger and a “dogging external sealing cap” on pipelines 4 inches and smaller. A rubber plumber’s plug is not an acceptable long-term locking plug.
  • Each end of the pipeline should be stabilized at the burial movement. Stabilization should be accomplished with an engineered solution based on seabed conditions and likely loads, or by utilizing proven industry practices. In shallow water, hurricane (typhoon) prone areas (such as the United States – Gulf of Mexico) a proven practice utilizes an auger-type anchor and steel cable to temporarily secure the pipeline end, followed by permanent stabilization with cement bag coverage.
  • Where an auger-type anchor is used to temporarily stabilize the end of a pipeline, it should be fully embedded and externally attached or looped to the pipeline end with a 1/2-inch cable. Cement bags (not simple sand bags) should be placed over the end of each pipeline to extend 6 feet in front of, 3 feet behind and 3 feet to each side past the end of pipe as a minimum. If allowed by regulations, requirements and agreements, concrete mats may be used in lieu of cement bags to cover the ends of the pipeline.
  • The resulting surface should be even with natural seabed surface and should not present an obstruction to navigation or commercial fishing (trawling) activities, e.g., the top of cement bags, concrete mats, etc. should not protrude above the natural seabed surface.
  1. Pipelines (or segments) that are removed should meet the following requirements:
  • Pipelines on the seabed surface may be severed in place, and then lifted or pulled to the surface, and transported to shore facilities for clean-up and disposal or salvage (material recycling).
  • Pipelines buried below the seabed surface should require excavation, severing and removal. Some seabed soil conditions may allow pulling of the pipeline out of the seabed to the surface without excavation, but caution must be used as obstructions (such as other pipelines or cables) may be hidden and could pose significant risks.
  • Pipelines are typically severed on both sides of crossings (other pipelines or cables) to eliminate the risk of damage at crossings during pipeline lifting or pulling to the surface, and then the pipeline segment under the crossing carefully removed.
  • If reverse-lay operations are employed, the subsea end of the pipeline segment should be sealed with a locking plug or cap to contain the contents during pulling to the surface. Plugs or caps should be mechanically attached and able to withstand the forces encountered without releasing. Examples of suitable locking devices include a “dogging type plug” on pipelines 6 inches and larger and a “dogging cap” on pipelines 4 inches and smaller. A rubber plumber’s plug is not an acceptable locking plug.
  1. Associated pipeline subsea infrastructure and appurtenances (such as pipeline manifolds, jumpers, pipeline end manifolds [PLEMs] and terminations [PLETs], anchors, pilings, concrete mats, riprap, cement bags, etc.) should be removed as required by national, regional and local regulations and requirements, concession terms and contractual agreements, and permit requirements, and as follows:
  • Subsea infrastructure and associated appurtenances in water depths of 200 feet and less should be removed, unless flush with or buried below the seabed surface.
  • Subsea infrastructure and associated appurtenances in water depths from 200 feet to 300 feet should be removed, unless flush with or buried below the seabed surface, unless they can be demonstrated through a risk assessment to not present a hazard (obstruction) to navigation, commercial fishing (trawling) activities or future use.
  • Subsea infrastructure and associated appurtenances in water depths greater than 300 feet do not have to be removed solely due to surface hazard (obstruction) considerations.
  1. Remove all concrete foundations, footings, and other subsurface infrastructure (such as drains and sumps) in coastal sites (onshore) that are included in offshore pipeline abandonment.
  2. Remove all pipeline surface minor equipment, piping and appurtenances associated solely with pipeline operation and safety, unless they will be removed during facility decommissioning or have future economic utility.
  3. Document final site condition and retain all records (including, for example, “as abandoned” drawings, before-and-after photos, videos or sonar scans, regulatory submittals, permits and approvals, contractual records, route maps and end points of abandoned-in-place pipelines, sampling reports, and inventory data).




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Tuesday, June 6, 2017

Gasket Selection

  Tadd       June 06, 2017       chemical , downstream , gas , guideline , midstream , offshore , onshore , petrochemical , petroleum , pipeline , terminal , topsides , upstream       No comments    


Compatibility with Fluid

The gasket should obviously not be affected by fluid being sealed over the whole range of operating conditions. If any doubt exists, then the gasket manufac­turer should be consulted.

Temperature

The gasket selected should have reasonable life expectancy at the maximum temperature encountered (or the minimum temperature if for a low temperature application). A broad indication of the tem­perature pressure ratings of the common gasket materials is shown in the figure below.



Gasket materials are designed to compress under load to achieve the initial seal. However, to retain that seal, the gasket should be able to resist flow (or creep) to prevent loss of surface stress by bolt reduction. This property is very important and is the one that most readily separates high quality from low quality gaskets.
Under ambient temperature conditions, most gasket materials do not creep significantly, but as the temperature rises beyond 100°C, creep becomes a serious consideration.
For all applications but particularly for low temperature applications, the following points should be observed:

  • The gasket should be completely dry when installed (gaskets for such applications should be stored in a dry atmosphere).
  • The required flange loading should be applied at ambient tem­perature.
Notes:

  1. The above information is intended as a guide to the maximum possible ratings of each class of jointing. It does not imply that all the gaskets within each generic type are suitable for the temperatures and pressures shown.
  2. Even if the material chosen is theoretically suitable for the tem­perature and pressure, other factors should be considered such as available bolting, flange facing type, shock loadings, etc.
  3. Consultation with gasket experts should take place at the design stage to ensure that the gasket selected is suitable for all conditions of the application.

Internal Pressure

The gasket has to be suitable for the maximum internal pressure experienced; this is often the test pressure, which can be greater than 2 times the flange rating at ambient temperature.
Vacuum conditions need special considerations but as a guide:
  • For coarse vacuum (760 torr to 1 torr): flat rubber or compressed asbestos fibre gaskets.
  • For high vacuum (1 torr to 1x10-7 torr): rubber ‘O’ rings or moulded rectangular seals.
  • For very high vacuum (below 1x10-7 torr): specialised seals required.

Special Considerations

There are many factors apart from those already considered that affect the selection of the correct gasket material and type.
  • Cycling conditions.
  • If the service conditions include frequent thermal or pressure cycles, then the gasket has to be resilient enough to allow for the flange movements and strong enough to resist the mechanical loading.
  1. Vibration: If the pipeline is subjected to undue vibration, then the gasket has to withstand the mechanical effects involved.
  2. Erosive Media: Certain media (e.g. solids suspended in liquids) can slowly erode gaskets leading to a much shorter life than expected. In such cases, choice of gasket material and selection of gasket dimensions are critical.
  3. Risk of Contaminating the Fluid: Sometimes the effect of contaminating the fluid by leaching chemicals from the gasket should be considered. Typical examples are in the sealing of potable water, blood plasma, pharmaceutical chemicals, food, beer, etc.
  4. Corrosion of Flanges: Some flange metals are prone to stress corrosion cracking (e.g. austenitic stainless steel). When using these, care should be taken to ensure that the gasket material does not contain an unacceptable level of leachable impurities which may induce corrosion. Such impurities include chloride ions.
  5. Integrity: When integrity of a gasket is of prime importance (e.g. when sealing a highly toxic chemical), the choice of gasket may be influenced by the requirement for a larger safety margin. As an example, a spirally wound gasket with an outer retaining ring may be selected in place of a compressed asbestos fiber gasket.
  6. Economy: Although a gasket is a relatively low priced item, the conse­quential expense of leakage or failure should be considered when deciding on quality, type and material of the gaskets.

Guidance

The following guidance is offered where pre-selection has not been carried out.

RTJ (Ring Type Joint) Gaskets

RTJ gaskets are forged rings that fit into the machined groove of an RTJ flange. RTJ gaskets are generally used for high pressure appli­cations. Sealing is by metal-to-metal contact between gasket and flange. Solid metal joint rings have excellent tightness and tolerance to temperature and pressure changes once correctly bolted up. Very close attention must be given to their bolting up. Rings and groove faces must be free of imperfections.
There are four different types of ring commonly available: Types R, RX, BX and AX. The most commonly used is Type R.
R Type
These are either oval or octagonal in cross-section. The oval RTJ is the original design. The octagonal RTJ is a modification to the oval design and provides better sealing. R type rings may be specified for Class 150 to 2500 flanges though are typically found on Class 1500 flanges and often Class 900. The piping specification will state whether an octagonal or an oval joint is to be used. R type rings may be used on either flat face or raised face RTJ flanges.
RX Type
RX gaskets fit and seal into the same groove sizes as do R type gaskets. Note that the RX gasket is wider than the R type gasket and the flange face-to-face separation will therefore be greater.
RX gaskets are normally specified up to Class 5000 API 6A Type B flanges. They are used when a more effective seal is required which is resistant to vibrations, shock loadings, etc. (e.g. on well­heads and Christmas trees).
The asymmetric cross-section makes the gasket self-energizing. The outside bevel of the ring makes the initial contact with the grooves of the flange and thus preloads the gasket against the groove outer surface.
BX Type
These are only used on API 6A Type BX flanges and are rated from Class 5000 to 15000.
The pitch diameter of the ring is slightly greater than the pitch diam­eter of the flange groove. This preloads the gasket and creates a pressure energized area.
Type BX gaskets are NOT inter-changeable with R or RX gaskets. The groove on a flange which accommodates a BX gasket is dimensionally different to that for R and RX gaskets.
When correctly fitted, the flange face-to-face separation using a BX gasket is zero.
Note: It is particularly important to check the flange face-to-face separation which must be uniform around the entire circumference of the flange. RTJ flanged joints are particularly susceptible to uneven bolt tensioning and misalignment of the ring within the groove.
AX Type
AX Ring Joint Gasket is pressure energized; the higher the pressure, the better the seal performance.
AX gasket is usually used for hydraulic connector, instead of heavy API interface flange with time-consuming installation. AX gaskets are primarily used in the oil, gas, petrochemical and offshore industries. They are also commonly used on valves, pipe-work assemblies and vessel joints and are used to seal flanged connections subject to high pressures and temperatures.

RTJ Gasket Identification and Specification

  1. Type: Whether R, RX or BX. If R, state whether octagonal or oval. The type of ring to be used will be specified in the piping specification.
  2. Ring Number: For example R46 will fit a 6 inch NB Class 1500 RTJ flange.
  3. Material: A variety of materials is available. Again check with the piping specification for the correct material. The material grade will have an identifying code. For example: Soft Iron: D; Stainless Steel 316 : S316
  4. Standard: Either ANSI B16.20 or API 6A; as specified in the piping specification (these two standards are equivalent and interchangeable).
  5. Identification: The type, ring number and material will always be marked on the side of the ring.

Spiral Wound (SW) Gaskets

The standard of SW gaskets can vary considerably between man­ufacturers, and they should be obtained only from reputable sup­pliers.
Most Spiral Wound Gaskets now being used are Spiral Wound 316 stainless/stainless Windings and Graphite Filler. These gaskets have a 316 stainless/stainless inner ring and coated carbon steel outer guide ring, but on some occasions the outer ring could be stainless steel to provide corro­sion resistance to the external environment.

Recommended Compressed Thickness
3.2 mm 2.3 -2.5 mm
4.5 mm 3.2 -3.4 mm
6.4 mm 4.6 -4.9 mm
7.2 mm 4.8 -5.0 mm



These gaskets are fitted with an internal guide ring which:
  • Provides an additional compression stop.
  • Restricts the lateral flow of the gaskets toward the bore.
  • Acts as a heat and corrosion barrier protecting the gasket and flange.
By filling the annular space between the gasket and flange, it reduces turbulent flow of the fluid or the possibility of the accumu­lation of solids, and possible corrosion.
The piping specifications for each individual plant will be changed to accommodate the new gaskets.
Spiral Wound Gaskets that may be present in flanges
  • Spiral wound gaskets are typically used on intermediate pressure systems and will be found on Class 300 flanges, Class 600 and Class 900 flanges.
  • SW gaskets are used on RF flanges with a smooth surface finish, as quoted in “Surface Finish Values for Flange Facings for Class 150 to 2500 Flanges”.
  • Where SW gaskets are used with standard Class 150 flanges and smaller sizes of standard Class 300 flanges, the higher seating load requirements and low bolting availability necessitates use of high strength bolting and proper bolting up procedures.
  • The use of gaskets with inner rings also increases the required bolting load.
Spiral Wound Section
  • This part of the gasket creates the seal between the flange faces. It is manufactured by spirally winding a preformed metal strip and a filler material around a metal mandrel. Normally the outside and inside diameters are reinforced by several additional metal windings with no filler.
  • When compressed, the combined effect of the metal winding and the filler material will make the seal. The filler material will flow into the grooves on the flange face and the metal winding will then strengthen and support the filler against the flange face.
Inner Metal Ring
  • The inner metal ring provides inner confinement to the gasket. Being of a specified thickness smaller than that of the uncom­pressed spiral windings, it acts as a compression stop, i.e. it pre­vents the windings from being over-compressed due to over-tensioning of the studbolts or thermal growth of the pipework when in operation. The inner ring also fills the annular space between the flange bore and the ID of the spiral wound section and therefore minimizes turbulence of the process fluids at that location and pre­vents erosion of the flange faces.
  • Note that the spiral windings should never be exposed to the flow of the process fluids. The ID of the inner ring should be flush with the bore of the flange and this should be checked prior to bolting up.
Outer Metal Ring
  • The outer metal ring acts as a compression stop and an anti-blowout device. It also centers the gasket on the flange face.
  • The spiral wound gasket should be centered on the flange with the outer ring resting against the studbolts. If this is not the case, the incorrect gasket has been chosen and should be changed.
Filler Material
  • For most applications in the petrochemical industry, an asbestos filler was usually specified. Asbestos is hazardous to health and even though trapped within the spiral winding, SW gaskets should be handled with care. Full procedures are available and should be consulted. Piping specifications now quote a "non­asbestos" filler instead of asbestos. Graphite filler has now taken over as being the preferred filler material.
  • For special applications other materials are available, such as graphite and ceramic fillers.
Spiral Wound Gasket Specification and Identification
Spiral wound gaskets are supplied and identified as follows:
  • NPS and Flange Pressure Class: A class and nominal pipe size must be specified and must match that of the flange con­cerned. The class and size of the gasket will always be stamped on the outer ring.
  • Flange Type: Spiral wound gaskets are normally used on RFWN flanges. If used on SO flanges, this should be stated as special gasket sizes will be required for NPS up to 1.5 inches.
  • Filler Material: A variety of materials is available. Normally asbestos was used but now graphite, PTFE, ceramic fillers, etc. are used predominantly. The filler material will be specified in the piping specification. Identification is by way of a color code on the spiral wound section.
  • Winding Material: Winding material is important as it should be resistant to the process conditions. The winding material will be specified in the piping specification and is typically stainless steel. Identification is by a color code on the outer ring.
  • Inner Ring: The inner ring will normally be the same material grade as the metal winding as it must equally resist the process conditions. Material grade will be specified in the piping speci­fication.
  • Outer Ring: Not such a critical parameter as the inner ring as it does not come into contact with process fluids. It is normally carbon steel and again will be specified in the piping specifica­tion.
  • Standard: Usually ASME B16.20, BS 3381 or API 601.
Spiral Wound Gasket Color Code Reference Chart
There are some process applications where graphite is unsuit­able. Refer to manufacturer's data sheets for details.
Winding Material Color Code
The outer ring of the SW gasket will be colored to identify the winding material. The ring may be only colored on the outer edge.
Carbon Steel Silver
304SS Yellow
316SS Green
347SS Blue
321SS Turquoise
Monel Orange
Nickel 200 Red
Titanium Purple
Alloy 20 Black
Hastalloy B Brown
Hastalloy C Beige
Inc 600 Gold
Incoloy White
Filler Material Color Code
The spiral wound section of the SW gasket will be colored to iden­tify the filler material, with flashes around the outer ring of the rele­vant color.
Non-Asbestos Pink
Graphite Grey
Asbestos None
PTFE White
Ceramic Light Green
Note that the above color coding is based on API 601.
When inspecting gaskets already fitted to flanges, it can be difficult to distinguish between white grey and light green. Users must be aware of this problem.

Sheet Gaskets

Non-Asbestos Fiber (NAF) gaskets have now replaced Compressed Asbestos Fiber (CAF) gaskets.
They are used for low pressure applications and are typically found on Class 150 and Class 300 flanges. They are normally used on Raised Face flanges (self-centering flat ring type gasket), but are also used on Flat Face flanges (full face type gaskets are required).
Tanged Graphite Gaskets
The used of Compressed Asbestos Fiber (CAF) gasket was predominant in the industry as the material covers a wide range of applications, but has a known health risk. The replacement gasket material which contains no asbestos has a stainless steel insert sandwiched between two layers of graphite. If not handled correctly, the insert may cut personnel. This type of gasket is known as a “tanged gasket”. The gaskets are non-stick, especially on stainless steel faces.
The stainless reinforcement increases the tensile strength of the material, its load bearing capacity and handling characteristics. It also improves its blow-out resistance under cycling conditions. For larger type gaskets, two stainless inserts may be used for greater rigidity and ease of handling.
Note: When handling this type of gasket, always use gloves.
The use of plain graphite gaskets is not recommended in oxy­genated seawater handling systems. For such duties, a non-asbestos utility gasket should be used.
The piping specifications for each individual plant should be changed to accommodate the new gaskets.
Utility Gaskets
In utility non-hydrocarbon services up to Class 300, where the tem­perature is below 100oC, and in equipment blinding applications, high performance nitrile rubber based reinforced sheet containing non-respirable glass fibers should be used.
Flat Rubber Gaskets
Flat rubber gaskets are normally found in the least hazardous and aggressive of conditions such as low pressure water services. Rubber gaskets are limited in use by temperature, pressure and chemical resistance. They are also liable to creep, e.g. if subjected to excessive bolt loading or repeated hydrotest.
Rubber gaskets are usually full face and are used on flat face flanges. Of the variety of rubbers available, that most commonly used as a gasket is Neoprene. Other rubber materials include natural rubber, Viton and Nitrile.
Rubber Gasket Specification and Identification
NPS and Flange Pressure Class: It should be marked on the gasket. If not, check the correct fit of the gasket on the flange. Alternatively, the gasket may be cut from rubber sheet. The bore of the pipe must not be restricted by the gasket and the entire face of the flange must be covered. Check the thickness of the gasket by reference to the piping specification.
Material: Whether Neoprene, Nitrile, etc., refer to the piping specification.

Gaskets for Lined Pipework

Joints in lined pipework are invariably flanged and gaskets often need to create a seal despite many of the linings being of a soft nature. Correct gasket selection is particularly important since:
  • Many linings, whilst having a smooth finish, have undulating sur­faces on the flanges due to the method of manufacture (e.g. glass).
  • There is usually a good reason for using lined pipework (e.g. chemically aggressive fluid or pharmaceutical fluid) and the gasket often has to be equal to the lining in terms of chemical resistance and freedom from contamination.
  • Linings tend to be of a fragile nature and bolt loads have to be kept low to prevent damage. This limits the choice of gasket material.
  • The gasket material has often to withstand the effects of aggres­sive cleaning fluids as well as the service fluids.

Types of Linings Available

Rubber Lined
A soft rubber gasket can be applied. A steel or ebonite spacer can be used to prevent over-compression.
Plastic Lined
Gaskets are not normally required, but there are exceptions:
  • where there are dissimilar flange connections (e.g. pipe to valve);
  • where the lining is too undulating;
  • where the lining is applied via a dripping process, e.g. PVC.
Lead Lined
Creep resistant PTFE or a PTFE envelope with soft rubber insert can be used.
Glass Lined
PTFE.



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Monday, January 30, 2017

Pipe Flange Surface Finish

  Tadd       January 30, 2017       chemical , downstream , gas , guideline , midstream , offshore , onshore , petrochemical , petroleum , pipeline , refinery , terminal , topsides , upstream       No comments    

Purpose

To create a seal, gasket has to fill up the voids in the flange surface present because of surface finish and any flange rotation (or relative distortion) between the two surfaces.
The flange surface will thus give a broad indication of which gasket materials are likely to be suitable. Finishes of standard raised face flanges usually fall within the range 3.2 to 12.5mm, but this may be expressed in micro inch or roughness number.


Surface Joining

The recommended surface finish for the compressed fibre jointing (above a thickness of 1 mm) is 3.2mm to 12.5mm Ra (125m in 500min. CLA). These values are also used for graphite laminate (above a thickness of 0.8mm).
A surface finish of 1.6mm to 6.3mm Ra (63 to 200 in. CLA) is possible for tongue and groove flange facings or for very thin gaskets (0.4mm or below).
Surface finishes below 1.6mm are not recommended due to their negative effect on creep resistance of the gasket.

Surface for Spiral Wound Gasket

This type of gasket requires a range of surface finishes dependent upon the application:
  • General - 3.2mm to 5.1mm Ra (125min. to 200min. CLA)
  • Critical - 3.2mm Ra (125min. CLA).
  • Vacuum applications - 2.0mm Ra (80min. CLA)

Solid Flat Metal Surface

A surface finish in the order of 1.6mm Ra is acceptable but for more critical conditions, a finish no more coarse than 0.8mm Ra is preferred. Again for optimum performance, the smoother the flange surface finish, the better the performance.

Surface for Metallic Ring Joint Gaskets

The angled surfaces (typically 23°) of both grooves and octagonal gaskets and the contact faces of oval gaskets should have a surface finish no rougher than 1.6mm Ra.

Machining of Flange Faces

Under no circumstances should flange seating surfaces be machined in a manner that tool marks extend radially across the seating surface. Such tool marks are practically impossible to seal regardless of the type of gasket being used.


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Monday, September 19, 2016

Liquefied Natural Gas (LNG) Overview

  Tadd       September 19, 2016       exploration production , gas , guideline , lesson learned , midstream , offshore , onshore , pipeline , presentation , terminal       No comments    

What is Liquefied Natural Gas?

  • Liquid methane that contains trace contaminants
  • Stored at atmospheric pressure & -161°C (-256°F)
  • Colorless, odorless, non-corrosive and non-toxic
  • Chemical composition (typical)
Read more...


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Thursday, September 8, 2016

Safety Shutdown Philosophy

  Tadd       September 08, 2016       chemical , downstream , drilling , gas , guideline , lesson learned , midstream , offshore , onshore , petrochemical , petroleum , pipeline , procedure , refinery , specification , subsea , terminal , topsides , upstream       No comments    

1. Abstract

The Safety Shutdown concept is focused on the prevention of hydrocarbon release, stopping the flow of hydrocarbon to a leak, and minimizing the effects of hydrocarbon that are released. Additionally, fire and toxic gas protection is also provided.
The primary goal is to maximize available production and at the same time to shore in a safety manner to equipment and personnel. This goal will be accomplished by employing a Keep It Simple and Safe philosophy and a Four-Level Shutdown concept.

2. Implementation

The basis for implementing the Safety Shutdown concept is the American Petroleum Institute Recommended Practice RP 14C. This Recommended Practice was used as a guide in developing the shutdown logic. API RP 14C provides two levels of protection to prevent or minimize the effects of an equipment failure. The two levels of protections are
  • The highest order (primary)
  • The next highest order (secondary)
Listed below are examples of undesirable events that cause alarm and/or shutdown action. This is not an all inclusive list, it is however illustrative of the protection philosophy.
  • Overpressure
  • Underpressure
  • Leak
  • Liquid Overflow
  • Gas Blow-by
  • Fired Equipment Protection
  • High Hydrogen Sulfide Concentration
  • Fire
Risk severity is divided into Four (4) Levels of Shutdown. These different risk levels will be utilized to protect equipment and personnel, while maintaining production as high as practical.
The shutdown levels are defined as follows:
Level 1: Local System Shutdown. It involves only services not imperative to the main process.
Level 2: Main Process Train Shutdown. It will allows continued operation of the remainder of the facilities and will permit the process train to be corrected and put back on stream.
Level 3: Critical Process Shutdown. The facility is shutdown by an essential single train process or by fire, high toxic gas, or combustible gas alarm. All ESD valves should be closed. All high pressure gas inventories should be relieved to flare only in the event of fire or high toxic gas alarm. Power generation should remain in operation until low fuel gas pressure causes shutdown. Utilities and equipment auxiliaries should remain in service as long as possible.
Level 4: Abandonment. It should be actuated only by senior personnel from the central control room. All ESD valves should be closed and all gas inventories should be vented to flare. The facility should be de-energized except for emergency and other essential power source.

3. Examples

Followings are specific examples that illustrate the Four Level Shutdown philosophy.
Level 1 (Local System Shutdown)
  • High or Low Pressure in an incoming flow line to a production header, would shut-in only the affected well.
  • The Water Injection System can be automatically shut down, but would not affect oil production.
  • The Hot Oil System can be automatically shut down, but would not affect oil production.
Level 2 (Main Process Train Shutdown)
  • A gas compression train can be automatically shut down, but would not affect the oil production.
  • An oil production train can be automatically shut down, and oil production affected only by volume loss from the affected train.
  • A gas turbine generator set can be automatically shut down. If the oil train pump can still maintain full production, no reduction in oil production is required. Otherwise curtailment of oil production or standby power augmentation should be required to prevent a level 3 shutdown.
  • The Glycol Regeneration Unit can be automatically shut down, but not affect Fuel Gas, Gas Lift Gas Flow or Oil Production. A facility shut down would occur only if the problem is not corrected before the residue gas moisture analyzer reaches the shutdown value.
Level 3 (Critical Process Shutdown)
  • Instrument air failure (automatic)
  • Leak detection in any main oil production header
  • Combustible gas sensors (automatic)
  • Fire sensors (automatic)
  • Hydrogen Sulfide sensors (automatic)
  • Critical Process Shutdown, i.e. Fuel gas (automatic)
  • Manual
Level 4 (Abandonment)
  • Manual initiation required by senior personnel only and would be confirmed over the public address system.
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Thursday, August 4, 2016

The Gateway to Capture Knowledge in the Energy Industry

  Tadd       August 04, 2016       chemical , datasheet , downstream , gas , guideline , lesson learned , midstream , petrochemical , petroleum , pipeline , presentation , procedure , refinery , specification , subsea , template , terminal , topsides , upstream       No comments    

What is Knowledge?
There are two types of knowledge that can be transferred between people and/or entities. A significant difference is between tacit and explicit knowledge:

Tacit knowledge is the stock of expertise and knowledge within an organization—primarily located within the brains of employees that cannot be easily expressed or identified, but may nevertheless be essential to its effective operation.

Explicit knowledge is the most visible knowledge found in practices, manuals, presentations, guidelines, documentation, files and other accessible sources.

The importance of knowledge management (KM) within the corporate environment as mentioned by Chevron’s former CEO, Ken Derr: “We learned that we could use knowledge to drive learning and improvement in our company. We emphasize shopping for knowledge outside our organization rather than trying to invent everything ourselves. Every day that a better idea goes unused is a lost opportunity. We have to share more, and we have to share faster.” BP’s former chairman and CEO, John Browne, similarly identified the central role of KM: “All companies face a common challenge: using knowledge more effectively than their competitors do.” The oilfield services leader Schlumberger’s D.E. Baird was saying that: “We must become experts in capturing knowledge, integrating and preserving it, and then making what has been learned quickly and easily available to anyone who will be involved in the next business decision.” The online knowledge-based OGnition also mentioned: “With worldwide knowledge in the energy industry, we offer to close the competency gaps in the workforce by leveraging the experience and technical knowledge of industry experts to address the challenges the industry faces today.”

Urged by a common goal of maintaining valuable knowledge, energy and services companies set out to adopt a strategy to establish their own sets of knowledge management. The table below shows how each company started its own Knowledge Management.

Company
Motive for Adopting Knowledge Management
BP
Following radical organizational decentralization, Knowledge Management viewed as mechanism for achieving lateral coordination
Shell
In Shell’s highly decentralized multinational structure, Knowledge Management was a natural complement to strategic planning and career management as an integrating mechanism. With poor profitability during early 1990s, Shell came under strong pressure to make more effective use of its dispersed talent
Chevron
Chevron’s adoption of Knowledge Management driven by pressure for cost reduction during early 1990s and as recent as 2015 resulted in strong interest in the transfer of best practices
ExxonMobil
XOM adopted Knowledge Management during the mid 1990s primarily by its desire to improve efficiency in E&P and in refining through improved identification and transfer of best practices
ConocoPhillips
Expansion of exploration, especially in deepwater Gulf of Mexico, created the need for data management systems to support large amount of data being generated and processed and link them to decision processes
Marathon Oil
Desire to improve upstream performance through more effective linking of people to people and people to information
Schlumberger
Knowledge Management came from the need to link rapidly advancing data management with systems that link human expertise in globally distributed operations
Halliburton
Fluor Corporation
Fluor started the Knowledge Management system, Knowledge OnLine, to enable employees throughout Fluor's worldwide offices to access corporate information and contribute solutions, lessons learned and expertise

When did Knowledge Management become recognized by companies?

Since the early 1990s, the major oil and gas companies as well as large services and consulting firms have realized that they are operating in a knowledge-based business environment where technical and safety performance must be achieved through the early identification of opportunities and potential issues that can arise, both from an organizational knowledge-capture perspective and as training to a transitioning workforce.

The following table illustrates the timing when companies started adopting Knowledge Management.

Company
Adoption of Knowledge Management
Originated for Knowledge Management
BP
1996
Organizational learning/best practices transfer in upstream
Shell
1995
Organizational learning initiatives by corporate planning
Chevron
1996
Best practices transfer and cost reduction
ExxonMobil
2003
Exxon: application of IT to E&P
Mobil: best practices transfer
ConocoPhillips
1998
IP support for E&P
Marathon Oil
1999
IP applications to exploration
Schlumberger
1997
IP applications to drilling
Halliburton
1998
IP applications to drilling
Fluor Corporation
1998
Collaboration and knowledge transfer

Why should we capture Knowledge?
  • Some select industries are faced with an aging workforce. The majority of the workforce, in fact, will be nearing retirement age over the next decade.
  • Between 2000 and 2010, the Society for Petroleum Engineers (SPE) estimated that 231,000 years of cumulative experience and knowledge will be lost to the industry in the next 10 years due to the retirement of petroleum engineers and other technical staff. Knowledge management offers a means of limited and potentially devastating effects of the continuous knowledge loss due to retirement & downsizing (Drain, 2001).
  • In order to make sure that this current gap does not turn into a future shortage, the industry needs to work in tandem with educational institutions and government to recruit and train people and transfer knowledge.
  • It is served as a hub for innovative technologies and thinking and as an industry striving to always improve in both good times and challenging times.
  • Since the energy industry is often challenged by fluctuations due to the world market, supply and demand, geopolitical conditions, etc. that makes sustaining the industry and workforce a huge challenge, a knowledge database can provide current and future industry professionals a means to exchange knowledge, collaborate and to address technical and commercial challenges facing the industry.

How can Knowledge Management help current and future professionals in the energy industry?

After the oil bust during 2008-2009 and as recent as Fall of 2014, more energy knowledge loss contributed by people taking early retirement, forced to move to a related industry and some taking a different approach of pursuing an entirely new career path. Knowledge Management is even more critical when baby boomers, born between 1946 and 1964, are heading into retirement in large numbers. If not managed properly, this could contribute to lost and irreplaceable knowledge in the industry.

Major companies have been going beyond occasional bilateral knowledge exchanges to form interactive groups that share knowledge in a rich, continuous and dynamic manner. Since 1998, all of the oil and gas majors have established informal or semi-formal groupings of employees that share common technical or professional interests for the explicit purpose of sharing knowledge. These knowledge-sharing groups go under a range of different names. For example, community types within ExxonMobil include: communities of Practice, Best Practice Communities, and Communities of Interest (ExxonMobil, 2003). Unfortunately, information gathered from these interactive groups’ knowledge sharing sessions often does not equate to real life experience that professionals can search for easily.

In order to mitigate the shortcoming to replace valuable knowledge, we need tools that capture the intangible assets of tacit knowledge for speedy exploitation to superior technology, management systems, innovation and know-how in order to achieve the competitive advantage in the industry, especially not to reinvent the wheels.

There are online forums and platforms that can help such as Google and Linkedin Groups that gear toward technical subjects. However, those groups are typically organized in an isolated subject or discipline. If one needs to learn across disciplines and various subjects, chances are that person needs to join multiple groups in order to get the information (s)he seeks to learn.

Fortunately, there is one online knowledge network, OGnition, that can connect those missing dots together. OGnition is an online community for the energy industry that offers knowledge and solutions in disciplines that range from upstream, midstream and downstream to occupational safety and operations. Anyone can ask a question to be answered by a Subject Matter Expert (SME) in their field of expertise. People can also share their accrued industry experience as lessons learned through posting as a blog or simply describing the factual events. Sharing lessons learned is the most valuable way to capture knowledge management that can be tagged and searched for and reused repeatedly.

The goal of knowledge management is to make sure that good experience gets repeated and bad incidents never ever happen again, to anyone, anywhere. Without knowledge sharing and lessons not-learned, we will keep making mistakes and reinventing the wheel.

Knowledge is meant to flow!




REFERENCES
Boyd, A. (2003): “Shell’s Communities of Practice: Ten Years On”. Presentation. January.
ExxonMobil Corporation (2003): Knowledge Management in ExxonMobil Upstream. Presentation, February.
Chevron Texaco Corporation (2002): The Chevron Texaco Way. San Francisco.
Derr, T.K. (1999): “Managing knowledge the Chevron way”. Speech given at Knowledge Management World Summit. San Francisco, California. Available at http://www.chevrontexaco. com/news/archive/chevron_speech/1999/99-01-11.asp
Drain, B. (2001): Retaining Intellectual Capital in the Energy Industry. Sapient Corporation.
Gartner Group (1999): The Knowledge Management Scenario: Trends and Directions for 1998-2003. Gartner, 18 March.
Hansen, M.T., Nohria, N. Tierney, T. (1999): “What’s Your Strategy for Managing Knowledge?”, Harvard Business Review, Vol. 77, num. 2, pp. 106–116.
KPMG Consulting (2002): Knowledge Management Research Report 2000. KPMG, October.
Grant, R. (2013): The Development of Knowledge Management in the Oil and Gas Industry, Universia Business Review.
OGnition (2016): Retrieved from http://www.ognition.com/about


NOTES
Contact author: Tadd Pham; https://plus.google.com/+TaddPham
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Wednesday, June 15, 2016

Types of Flanges and Facings and Its Uses

  Tadd       June 15, 2016       chemical , downstream , gas , guideline , lesson learned , midstream , petrochemical , petroleum , pipeline , procedure , refinery , specification , subsea , terminal , topsides , upstream       2 comments    

Types of Flanges

Weld-Neck Flange
The Weld-Neck flange is butt-welded to the pipe. Weld-Neck flanges are typically used on extreme duties such as high pressures and/or hazardous fluids. The butt weld may be inspected by radiography or ultrasonic as well as Magnetic particle Inspection (MPI) or Dye Penetrant Inspection (DPI) during fabrication. There is therefore a high degree of confidence in the integrity of the weld. A butt weld also has good fatigue performance and its presence does not induce high local stresses in the pipe work.


Slip-On Weld Flange
Used typically on low pressure, low hazard services such as fire water, cooling water, etc. The pipe is “double-welded” both to the hub and the bore of the flange and again radiography is not practical. MPI or DPI will be used to check the integrity of the weld. Where specified, the Slip-On flange will be used on pipe sizes greater than 1.5 inches with a preference for the Socket Weld flange for sizes up to and including 1.5 inches.

Threaded Flange
Threaded flange is similar to that of Slop-On flanges except the bore of threaded pipe flange has tapered threads. Threaded flanges are often used for small diameter, high pressure requirements. The benefit of threaded flanges is that it can be attached to piping without welding.

Socket Weld Flange
Socket weld flanges are often used on high pressure, hazardous duties but will be limited to a nominal pipe size (NPS) of 1.5 inches. The pipe is fillet welded to the hub of the SW flange. Radiography is not practical on the fillet weld and correct fit-up and welding is therefore crucial. The fillet weld will normally be inspected by MPI or DPI.

Lap Joint Flange
Comprises of a hub or “stub end” welded to the pipe and a backing flange or capped flange which is used to bolt the joint together. This type of flanged joint is typically found on cunifer (Cu/Ni/Fe) and other high alloy pipe work. An alloy hub with a galvanized steel backing flange is cheaper than a complete alloy flange. The flange has a raised face and sealing is with a flat gasket such as a compressed asbestos fiber (CAF) sheet gasket.

Blind Flange
Blind flange is round plate without a bore and used to blank off the ends of piping, valves, and nozzles on pressure vessel openings. Blind flange is used for testing the flow of gas or liquid through a pipe or vessel and also allow easy access in case work must be done inside the piping or vessel.

Swivel Ring Flange
Similar to the Lap Joint Flange, a hub will be butt welded to the pipe. A swivel ring sits over the hub and allows the joint to be bolted together. Swivel Ring Flanges are normally found on subsea services where the swivel ring facilitates flange alignment. The flange is sealed using a Ring Type Joint (RTJ) metal gasket.


Types of Flange Facings

Raised Face (RF)
Sealing on a RF flange is by a flat non-metallic gasket (or a flat metallic gasket for special applications), which fits within the bolts of the flange. The facing on a RF flange has a concentric or phonographic groove with a controlled surface finish. If the grooves are too deep (or a rough surface finish), then high compression is required to flow the relatively soft gasket material into the grooves. Too shallow (exceptionally smooth surface finish) and again high compression is required as a leak path then becomes more possible. It is important to always check the flange surface finish for imperfections which would make sealing difficult. A radial groove for example is virtually impossible to seal against.
The surface finish on the flange facing depends on the type of gasket being used.

Flat Face (FF)
Sealing is by compression of a flat non-metallic gasket (very rarely a flat metallic gasket), between the phonographic/concentric grooved surfaces of the mating FF flanges. The gasket fits over the entire face of the flange. FF flanges are normally used on the least extreme duties such as low pressure water drains and in particular when using cast iron, cunifer or bronze alloy, where the large gasket contact area spreads the flange loading and reduces flange bending.
Both ANSI B16.5 and BS 1560 specify Flat Face Flanges and Raised Face Flanges as well as RTJ Flanges. API 6A is specific to RTJ flanges only.

Ring Type Joint (RTJ)
Typically found on the most severe duties, for example high pressure gas pipe work. Ring type metal gaskets must be used on this type of flange facing.
  • RTJ to API 6A Type B, BS 1560 and ANSI B16.5: The seal is made by metal-to-metal contact between the gasket and the flange groove. The faces of the two opposing flanges do not come into contact and a gap is maintained by the presence of the gasket. Such RTJ flanges will normally have raised faces but flat faces may equally be used or specified.
  • RTJ to API 6A Type BX: API 6A Type BX flanges seal by the combined effect of gasket compression and flange face-to-face contact and will therefore always have raised faces. The flanges also use special metal ring joints. A Type BX flange joint which does not achieve face-to-face contact will not seal and should not be put into service.

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