3.0 GENERAL REQUIREMENTS
3.1 Design Considerations
3.1.1 Unless otherwise noted in the specifications, all pressures and temperatures referred to shall be considered Design Conditions. Design Conditions shall be as defined in Doc. No....
3.1.2 Piping component wall thicknesses are based on pressure design thickness, taking into account the specified corrosion allowance and any permitted manufacturer under tolerance. Piping component wall thickness does not include additional thickness that may be required to compensate for design considerations such as thermal loads due to restraints, live loads, hydraulic shock, loads on underground pipe, or loads or forces from other Reference(s). Additional loads will need to be considered in the design of piping systems.
3.1.3 Unless otherwise indicated in the specifications, piping components are specified to be adequate for the full flange rating of the pressure class.
3.2 Line Class Notes
3.2.1 Each pipe specification contains specific numbered notes (in parenthesis) that pertain to one individual component or to a group of components, as well as a list of additional requirements that pertain to the entire specification.
3.2.2 Line class notes are provided in page 4 of this Standard. The information contained in these notes shall be read and adhered to ensure compliance with the line class specification.
3.3 Item Descriptions
3.3.1 The item descriptions on the individual line class are abbreviated, and may be used for purchasing the item with the exception of Valves. Abbreviations are contained in page 4 of this Standard.
3.2.2 The complete purchase description for Valves is contained in the Valve specifications, and shall be followed to ensure compliance with the pipe specifications.
4.0 SPECIFIC REQUIREMENTS
4.1.1 Welded pipe shall not be substituted for seamless pipe. Seamless pipe may be substituted for welded pipe in all services, sizes and materials.
4.1.2 Where "CALC" is specified for piping material wall thickness, the wall thickness shall be calculated in accordance with the applicable ASME B31 Code.
4.1.3 Stainless steel, electric fusion welded (EFW) pipe (ASTM A 358) may be substituted for ASTM A 312 EFW pipe for sizes 14 in. NPS and above.
4.1.4 Carbon steel seamless pipe, ASTM A 106B, may be substituted for ASTM A 53B, Type S, and seamless pipe in all sizes.
4.1.5 Where joint factors are specified for pipe, these factors shall be taken as minimum values. Use of pipe with joint factors in excess of these values is acceptable. If pipe manufactured with a higher joint factor than listed on the specification is used, the minimum joint factor listed on the specification shall be used when calculating wall thicknesses of the pipe.
4.1.6 Double Submerged Arc Welded (DSAW) pipe shall be used for all EFW stainless steel pipes. If DSAW pipe is not available, EFW pipe with a single butt joint having a joint factor of 0.80 shall be used for 8 in. NPS and smaller.
4.2.1 Welded fittings shall not be substituted for seamless fittings. Seamless fittings may be substituted for welded fittings in all services, sizes and materials.
4.2.2 Dimensions of all fittings shall be in accordance with the industry standard referenced on the individual specification.
4.2.3 Buttweld fittings shall have a wall thickness to match the wall thickness of the adjoining pipe. Fittings of commercially available wall thickness shall be used even though the fitting may have a slightly larger wall thickness than the adjoining pipe. The ends of the fitting shall be taper bored if the thickness of the fittings exceeds that of the pipe by more than 1/16 in. (1.6 mm). Taper boring shall not result in an infringement on the minimum wall thickness.
4.2.4 Long radius elbows are required for all buttweld elbows. Short radius elbows shall only be used with "Client" approval.
4.2.5 Use of Lokring® Fittings
LOKRING® fittings are generally recognized in the industry as a robust pressure containing device that can be easily and quickly installed without a hot work permit. These features can be highly attractive when considering the installation cost. However, there is limited experience within "Client" on the overall long term performance for these fittings, so the potential for long term reliability and maintenance issues must be considered, such as inspection limitations and the potential for crevice corrosion, water freeze damage and stress corrosion cracking due to the inherent crevice between components and the high sealing stresses. For these reasons LOKRING fittings are considered an acceptable alternative for use in pipe specifications provided all the limitations described below have been met..
4.3.1 Dimensions and surface finishes of all flanges shall be in accordance with the industry standard referenced on the individual specification.
4.3.2 Buttweld flanges shall have a wall thickness to match the wall thickness of the adjoining pipe. Flanges of commercially available wall thickness shall be used even though the flange may have a slightly larger wall thickness than the adjoining pipe. The end of the flange shall be tapering bored if the thickness of the flange exceeds that of the pipe by more than 1/16 in. (1.6 mm). Taper boring shall not result in an infringement on the minimum wall thickness.
4.3.3 Orifice flanges shall be Class 300 minimum. Orifice flanges shall be ordered in pairs and shall have Socketweld taps. Class 150 utility services, specifications PLC... and PLC..., may use threaded orifice taps.
4.3.4 When mating to cast iron flat-face flanges is required, a carbon steel flat-face flange with a full-face gasket shall be used. Full-face gasket material shall be compatible with process stream and shall be in accordance with Doc. No... requirements.
4.3.5 When mating to cast steel flat-face flanges is required; a raised-face flange shall be used. The gasket shall be of a type and material that meets the requirements of the piping specification.
4.3.6 Flanges installed in acid/caustic service (as defined in Doc. No...) or other hazardous material shall be protected with a flange safety shield when a potential for exposure to personnel and/or equipment exists.
4.4 Branch Connections
4.4.1 ASME B16.9 welding tees shall be used when branch connections are size on size. Reducing tees shall be used when the branch run is one nominal size less than the header run.
4.4.2 Except where indicated on the individual line classes, integrally reinforced branch connections shall be used for branch runs NPS 8 and smaller.
4.4.3 Full area replacement shall be used for branch connections above NPS 8. The reinforcing pad thickness shall equal the header thickness, and the reinforcing pad width shall equal 1/2 the outside diameter of the branch. The material of the reinforcing pad shall match the material of the header.
4.4.5 If an economic incentive exists, the dimensions of the reinforcing pad may be calculated in accordance with ASME B31.1 or ASME B31.3 as applicable. In this case, "Client" shall approve dimensions of reinforcing pads.
4.5.1 Gasket types shall be as indicated on the individual piping specification and shall conform to the additional requirements of Doc. No....
4.5.3 Inner rings are required on all spiral wounds PTFE filled gaskets.
4.5.4 Inner rings are required on all spiral wound graphite filled gaskets.
4.6.1 Valve tag numbers are listed on the individual piping material specification. The individual Valve specification sheet for the tag number and the requirements defined in Doc. No... shall be met to ensure compliance with the line class specification.
4.6.2 The basic Valve design shall be in accordance with the referenced standard on the valve specification sheet. Valves designed in accordance with API 600 may be substituted for ASME B16.34 Valves.
4.6.3 The following Industry Codes/Standards apply to the specific design aspects of valves..
|Pressure / Temperature Rating
|ASME B16.34 (Excluding API Class 800) API 602
|End Flange Dimensions and Surface Finish
|ASME B16.5 (NPS 2 thru 24)
ASME B16.47 (NPS 24 and above)
|Socketweld / Threaded Ends
|Buttweld Ends Bore Size
4.6.4 API trim numbers specified on non-API Valves are for reference only. The trim number defines the minimum requirements for Valve trim.
4.6.5 Bonnet gaskets shall be as specified on the Valve specification sheets. When PTFE based gaskets are used; the gasket shall be fully confined on both the inner and outer diameter.
4.6.6 Class 150 Gate Valves with oval Bonnet design that cannot fully contain a PTFE based gasket shall use the manufacturer's standard metal Bonnet gasket. The gasket shall meet the requirements defined in API 600, and shall be of metallurgy compatible with the intended fluid service.
4.6.7 Full port Ball Valves shall only be used with prior "Client" approval.
4.6.8 When both a lift Check Valve and a swing Check Valve are specified, the following criteria shall apply..
4.7 Assembly Details
4.7.1 Assembly details on individual specifications are for reference only. Branch connections and block Valves for take-offs shall be specified in the specification. The following requirements apply to the assembly details on the specifications.
4.7.2 Pipe nipples shall be fabricated from line class pipe. Length of pipe nipple shall be adequate to clear insulation.
4.7.3 When a threaded x Socket Weld Valve is specified for assembly details, the Valves shall be welded to the pipe nipple. A line class threaded plug shall be used for plugging threaded and threaded Socket Weld vent and drain Valves.
4.7.4 When a flanged Valve is specified for assembly details, a line class flange shall be used on the pipe nipple for mating. A line class blind flange and gasket shall be used for plugging flanged end vent and drain Valves.
4.7.5 Valved vent shall be provided at every high point.
4.7.6 All underground piping shall be coated and wrapped in accordance with Doc. No....
4.7.7 Flange bolt up shall be per Doc. No.....
4.8 Testing and Examination
4.8.1 Unless otherwise specified on the individual line class specification, all non-destructive examination shall be in accordance with Doc. No....
4.8.2 Radiography, as required for special service piping and non-ferrous materials, shall be in accordance with ASME B31.3 and Doc. No....
4.9 Pressure/Temperature Limits
4.9.1 Pressure/temperature limits are based on ASME B16.5. Maximum and minimum temperatures shall be in accordance with Doc. No....
4.9.2 Stainless steel specified as Dual Marked/Dual Certified (i.e., 304/304L, 316/316L) may be used at the pressure/temperature rating and the allowable stress of the straight grade stainless steel through 800°F (427°C). Use of this material specification is limited to 800°F (427°C).
4.9.3 For piping systems not designed and installed per these specifications, the use of the higher pressure/temperature rating and allowable stress for dual marked stainless steel is not permitted.
4.9.4 The use of stainless steel marked and certified to only one grade of stainless steel is permitted at the pressure/temperature rating and allowable stress of the grade marked on the piping components.
4.9.5 Actual pressure or temperature limits for specifications may be reduced due to limitations on individual components such as pipe wall thickness, gasket materials or Valve internals. Individual specification shall be consulted to determine any limiting components for a specification.
4.9.6 For specifications where the Valve's material is not the same as the flange material, the pressure/temperature rating shall be based on the component with the lower pressure/temperature rating.
4.10 Miscellaneous Components
4.10.1 See page 5 for steam trap detail installation, page 11 for strainers and page 15 for spectacle blinds.
4.10.2 Flexible components such as metallic hoses shall only be used in accordance with plant specific requirements and procedures. As a minimum, the temperature rating and pressure class of the metallic hose shall meet the applicable pipe specification pressure and temperature rating. Written engineering approval is required for plant sites without applicable procedures.