Applicable Codes and Standards
- Material supplied shall be strictly in accordance with the latest codes and standards, mentioned in the Material Requisition Scope of supply. This specification for pipes, fittings and flanges as detailed in subsequent clauses shall supplement the codes and other project specifications.
- Dimensions of Carbon steel / Stainless steel / Alloy steel pipe shall comply with ASME B36.10M or ASME B36.19M as applicable.
- All items shall be supplied in accordance with the wall thickness or schedule as stated in Inquiry / Purchase requisition. Wall thickness heavier or thinner than specified tolerance shall not be accepted.
- For all piping components, material type and grade together with NPS and schedule / wall thickness / class shall be as specified in the description within the Material requisition – Scope of Supply.
- Butt weld end preparation for pipes, fittings and flanges shall be as per ASME B16.25.
- Plain end pipes shall have ends square cut with burrs removed.
- All threaded & coupled pipes shall be supplied with ends threaded in accordance with ASME B1.20.1 (NPT).
- Each length of the threaded pipe shall be supplied with full coupling screwed hand tight at one end.
Welded Seam Pipes
- All welded items shall be 100% radio graphically examined to give a joint factor of 1.0. Pipes and fitting shall be supplied seamless unless otherwise specified. Seamless is an acceptable alternative for welded pipe and fittings and vice-versa are not acceptable.
- Welded pipe shall be supplied with single straight seam for sizes upto 36” and double straight seam for sizes greater than 36” subjected to approval from the contractor.
- Spiral seam welds are not acceptable.
- All DSS welded pipes with a wall thickness greater than 30 mm shall also be 100% ultrasonically examined.
Material of Construction
- The chemical analysis of CS & LTCS pipes and fittings, forgings, plates shall be in accordance with the applicable product standard with the following limitations:
Carbon 0.23 Maximum wt% (pipes)
Carbon 0.23 Maximum wt% (forgings)
Carbon Equivalent CE shall not exceed 0.43%
Where CE = C + Mn/6 + (Cr+Mo+V)/5 + (Cu+Ni)/15
- The above formula for CE is applicable when the carbon content is greater than 0.12%
- All CS & LTCS materials shall be fully killed and fine grained and shall be produced by a low sulphur and low phosphorous refining process. The components shall be shall be supplied in normalized or normalized and tempered condition.
- All Austenitic stainless steel, duplex stainless steel items shall be supplied in solution annealed and quenched condition as per corresponding ASTM standard.
- The carbon content of SS 316 shall not be more than 0.03%. All SS Materials specified as F316 / WP 316/ Type 316 may be dual certified for both SS 316 & 316L, if specifically mentioned in the project specification.
- Austenitic stainless steel shall be capable of passing an inter-granular corrosion test in accordance with ASTM A262, Practice E.
- All duplex stainless steel shall have ferrite content (volume fraction) between 35% – 65% on base metal and on heat affected zone to 35% to 70 % as per ASTM E562 four point count method.
- Carbon steel pipes shall be supplied in double random lengths (11 to 13m) for pipe sizes 2″ to 36”, and in single random lengths (5 to 7m) for pipe sizes 1.5″ and smaller.
- SS, DSS and CS galvanized pipes shall be supplied in single random lengths (5 to 7m) for all pipe sizes.
- Jointers are not acceptable. It is not permitted to join lengths of pipe by circumferential welds to make single or double random lengths.
- Galvanizing of pipes shall be in accordance with ASTM A153. Threaded portion of pipes shall be free of galvanizing.
- Pipes shall be heat treated in accordance with product specification requirements after completion of all forming and welding operations.
- CS & LTCS Pipes shall be fully killed, fine grained and shall be supplied in normalized or normalized and tempered condition. All stainless steel pipes shall be supplied in solution annealed condition.
Sour service requirements
- All materials specified for sour service shall, as a minimum, meet the requirements of NACE MR0175 / ISO 15156 – latest edition.
- All welded pipes / fittings in sour service shall be HIC tested, if required by the project specification. It shall be conducted for one pipe / fitting per heat in accordance with NACE TM-0284 Solution – A with acceptance criteria as specified in NACE MR-0175.
- All CS, LTCS, welded austenitic and duplex stainless steel piping components shall be impact tested in accordance with ASME B31.3.
- For carbon steel pipes and fittings, the impact test temperature shall be the ‘minimum metal temperature’ as defined in the project. The impact test requirement and acceptance criteria shall be as per Cl. 323.2.2 and Cl. 323.3.5 of ASME B31.3 respectively.
- For LTCS items, the impact test temperature shall be (-460C). Test results shall be atleast 27 joules as an average of three tests (for standard specimen 10 x 10 mm), oneresult may be lower, but not lower than 21 joules.
- For welded SS and DSS items, the impact test temperature shall be the ‘minimum metal temperature’ as defined in the project but not more than (-1010C) and (-500C) respectively. For SS items, the acceptance criteria shall be as per Cl. 323.3.5 of ASME B 31.3. For DSS items, test results shall be at least 40 joules in transverse direction (for standard specimen 10 x 10 mm) as an average of three tests, one result may be lower but not less than 30 joules.
Positive material identification
Positive Material Identification (PMI) shall be conducted for all SS / CRA alloy piping items as per the project specification included in the Inquiry / Purchase requisition.
Marking and Colour Coding
- Marking of the piping components shall be done as per applicable codes and standards in addition to piping item/part number, purchase order number specified in Material Requisition Scope of supply. For the material specified as sour service, LT, CRYO in Material Requisition Scope of supply, the marking shall include “Sour”, “LT”, and “CRYO” respectively.
- If punching or die stamping is used for carbon, low temperature and alloy steel, the stamps shall be of low-stress stamps (dot or round bottomed). For stainless steel stamping shall be electro etched. If stenciling is used, it shall be done by indelible paint. For sizes below 1.1/2” and below the markings shall be done on attached metal tags.
- Colour coding of piping components shall be done based on the material categories as identified in project specification attached with Inquiry / Purchase requisition.
Packing and Preservation
- Material shall be packed ready for export in a manner which allows easy handling and prevents damage. Vendor shall submit their standard packing procedure to purchaser for approval.
- Pipe ends shall be protected with heavy duty plastic end caps. For beveled ends, the caps shall cover the full area of the bevel.
- Thin wall pipes shall not be overloaded with multi layer of pipes while shipping. All thin wall pipes shall be braced suitably at the end to avoid ovality.
- Water proof barrier material shall be used for stainless steel materials to protect against chlorine attack by exposure to salt water atmosphere.
- Carbon steel and stainless steel items are not allowed to be stored together and shall be packed separately.