API 5L: Specification for Line Pipe (X42 to X70)

Overview

API 5L is the American Petroleum Institute specification for seamless and welded steel line pipe used in pipeline transportation systems. It organizes grades by specified minimum yield strength and distinguishes product specification levels with different technical and documentation requirements. The grade, PSL, manufacturing process, wall, toughness test temperature and acceptance criteria, sour-service qualification, coating and inspection plan must come from the pipeline design and project specification. A higher X grade does not by itself authorize a thinner wall or higher pressure, and PSL2 is not a universal default for every line. If a proposed pipe also falls within an Indian boiler boundary, the approved design and competent authority must establish the permitted material and component classification. Where the official form route applies, a steam pipe maps to Form III-A rather than generic Form III-C.

What API 5L is, and what it is not

API 5L is a line-pipe specification for pipeline transportation of petroleum and natural gas. It is not a water-class ERW standard and it is not a boiler-tube standard.

API's 46th-edition announcement page retrieved on 2026-09-03 is titled API Specification 5L: 46th Edition. It names PSL 2 pipe for sour service and PSL 2 pipe for offshore service among the key changes.

A separate API news release dated 2 June 2026, also retrieved on 2026-09-03, announces publication of the 47th edition of API Spec 5L, Line Pipe. That release says the 47th edition adds requirements across more than 15 topic areas, including high-frequency weld pipe quality and pipe used in CO2 transport. It also states that Spec 5L covers manufacture of seamless and welded steel pipe: material, process, inspection, testing, marking and traceability.

This page's specs still cite API 5L (45th Edition, 2012) or later. Quote the edition written in the pipeline specification, and do not mix 45th, 46th and 47th requirements on one PO without the project engineer's note.

ISO 3183 is the ISO counterpart for steel pipe in pipeline transportation systems. Treat it as a related document, not an automatic substitute, unless the tender names it.

IS 3589 water pipe and IS 1239 utility tube are different Indian conveyance standards. Similar OD does not make them API 5L line pipe.

Who should buy API 5L from a Kanpur enquiry

Use API 5L when the approved pipeline specification names it. Do not assign X42 through X52 to gathering lines, X60 through X65 to interstate lines, or X70 to high-pressure work from a generic application ladder. Grade and wall require the governing pressure calculation, design factor, diameter, temperature, corrosion allowance, installation loads, fracture-control basis, construction route and approved project requirements.

Specify PSL1 or PSL2 exactly as the adopted edition and project documents require. Service importance, toughness, traceability, NDE, sour conditions, offshore conditions and supplementary requirements must be assessed together. A website label such as low pressure or critical is not a selection rule.

Do not infer an IBR boiler route from API 5L or PSL level. The approved design must establish the permitted material and component. If a steam pipe is accepted into an IBR scope, verify the applicable Form III-A and supporting inspection records with the competent authority.

Do not use API 5L as a silent substitute for IS 3589 municipal water mains unless the tender permits it, since coating, lining and hydrotest language differ.

For H2S service, state the complete environment and the exact API 5L sour-service and ISO 15156 requirements adopted by the project. Do not infer qualification from PSL2 alone, or append a generic hardness number without the applicable material table, manufacturing condition, test method, locations and acceptance basis.

Grade selection: X42 through X70

API 5L grade designations encode specified minimum yield strength, but that is only one input to design. X42, X52, X56, X60, X65 and X70 each have edition-, PSL-, size-, wall- and product-form-dependent requirements that must be read from the adopted specification.

Do not associate one grade with a universal pressure, distance or diameter range. Pressure containment, fracture resistance, installation strain, fatigue, corrosion, weldability, availability and life-cycle economics depend on the complete design and material basis.

A higher grade can change the calculated wall for a defined design, but procurement cannot perform that substitution from yield strength alone. Any grade or wall change must return to the responsible pipeline engineer and be reconciled with welding procedures, toughness, NDE, coating, field construction and authority requirements.

PSL1 vs PSL2: which product specification level?

PSL1 and PSL2 carry different requirements. State the level selected by the project, then copy its grade-, size-, process-, service-, toughness-, NDE-, traceability-, and supplementary requirements into the purchase order.

PSL1 is the base specification, covering chemical composition, mechanical properties and dimensional tolerances. It permits carbon equivalent (CE) up to 0.43% for Grade B and up to 0.45% for X42 to X52. PSL1 does not require mandatory notch toughness testing or NDE (non-destructive examination).

PSL2 adds mandatory fracture toughness requirements (Charpy V-notch), restricts carbon equivalent for improved weldability, requires NDE (ultrasonic or radiographic) and mandates full traceability. PSL2 pipes are stamped with the grade and PSL level.

The project must select PSL1 or PSL2 from its governing risk, design, regulatory, service, toughness, inspection and documentation basis. Do not approve PSL1 from a low-pressure label or PSL2 from a cross-country label; reproduce the adopted requirements and acceptance criteria instead.

Chemical composition (PSL2 typical)

• Carbon: 0.18% max (X42 to X52), 0.18% max (X56 to X70), controlled for weldability
• Manganese: 1.20-1.50% max depending on grade
• Phosphorus: 0.025% max (PSL2)
• Sulphur: 0.015% max (PSL2)
• Carbon equivalent (CEIIW): 0.43% max (X42 to X52), 0.45% max (X56 to X65), 0.46% max (X70)
• Vanadium, Niobium, Titanium: Micro-alloying elements for strength (0.05-0.15% total)

Mechanical properties (PSL2)

• Yield strength: X42 = 289 MPa, X52 = 359 MPa, X56 = 386 MPa, X60 = 414 MPa, X65 = 448 MPa, X70 = 483 MPa
• Tensile strength: X42 = 414 MPa, X52 = 455 MPa, X56 = 490 MPa, X60 = 517 MPa, X65 = 531 MPa, X70 = 565 MPa
• Elongation: Specified by equation based on tensile strength (typically 20-25% min)
• Charpy V-notch: test temperature, specimen orientation and acceptance values depend on the adopted edition, grade, size, wall, design and project requirements
• Sour-service hardness: use the applicable API 5L and ISO 15156 material route, test method, locations and acceptance criteria for the defined environment

How to specify API 5L on an RFQ

Line-pipe RFQs fail when they say "API 5L X52" and leave out PSL, process, coating and toughness temperature. Write the pipeline spec line, not a stock nickname.

• Standard and edition: API 5L, plus 45th, 46th or 47th as the project document states
• Grade: B, X42, X46, X52, X56, X60, X65, X70 (higher grades only if the design uses them)
• PSL: PSL1 or PSL2 exactly as selected by the approved pipeline specification
• Process: seamless (S), ERW, LSAW or SSAW
• Size: OD and wall, or NPS and schedule, with D/t if the spec uses it
• Length: SRL 6-12 m or DRL 11-13 m, random or cut-to-length
• End finish: plain, 30° bevel, or threaded with couplings
• Coating: external FBE, 3LPE or 3LPP; internal epoxy or bare
• Certificate: API 5L MPS, MTC 3.1/3.2, plus NACE wording if sour
• Inspection, packing, quantity in metres or MT, delivery basis

Worked mass example: 6 inch NPS Sch 40 line pipe

The pipe schedule chart gives 6 inch NPS (DN 150) as OD 168.3 mm and Sch 40 wall 7.11 mm. Mass uses W = (OD - t) × t × 0.02466 kg/m.

(168.3 - 7.11) × 7.11 × 0.02466 = 161.19 × 7.11 × 0.02466 = 28.26 kg/m.

One kilometre of that wall weighs 1,000 × 28.26 = 28,260 kg, which is 28.26 MT before coating.

3LPE or FBE mass sits on top of the steel figure. Do not use the bare-pipe tonne for coated freight. State coating on the RFQ so the mill quotes steel plus coating as the spec requires.

There is no API 5L rupee band on the site price lists. Seamless A106/A53 bands are a different product. Ask for a proforma on grade, PSL, OD, wall and coating.

Common mistakes on API 5L procurement

PSL is selected from price or a marketing label instead of the approved specification, leaving toughness, NDE, chemistry, traceability and supplementary requirements unresolved.

Grade X65 PSL1 is treated as interchangeable with X52 PSL2, but grade is strength and PSL is testing. They do not replace each other.

ERW is offered against an LSAW large-diameter item, or seamless is offered against a spiral-weld trunk. Process is a specified field.

Sour service is assumed from API 5L or PSL2 alone. State the H2S environment and the complete project-approved ISO 15156/API material, condition, hardness, testing and documentation basis.

IS 3589 water pipe is delivered against an API 5L line because OD matched. Authority engineers often reject the substitution at stringing.

Standards and compliance for Indian jobs

The governing line-pipe document is API Specification 5L. ISO 3183 is the ISO counterpart named in this page's sources.

API's 46th-edition announcement (retrieved 2026-09-03) updates mill jointers, pipe-end squareness and hardness testing on PSL 2 pipe for sour and offshore service. It also adds a strain-based design annex for PSL 2 pipe needing longitudinal plastic strain capacity.

Do not reuse one Charpy test temperature or energy value across every PSL2 grade, size, wall, product form or project. Write the test temperature, specimen basis, acceptance values, NDE scope and chemistry controls from the adopted edition and pipeline specification.

NACE MR0175 / ISO 15156 may apply where the approved sour-service design invokes it. If a pipe also enters an IBR scope, classify it and verify the component-specific route. The official forms index assigns steam pipes to Form III-A, not Form III-C.

Key points

• API 5L is line pipe for oil and gas. It is not IS 1239 utility tube and not SA192 boiler tube.
• API announced the 46th edition of Spec 5L, and on 2 June 2026 announced the 47th. Quote the edition on the PO.
• X42 yield is 289 MPa; X70 yield is 483 MPa. PSL2 is the usual Indian transmission requirement.
• 6 inch NPS Sch 40 is 168.3 mm OD × 7.11 mm wall and 28.26 kg/m on the site schedule chart.
• Write PSL, process, coating and sour-service wording. Grade alone is not a complete RFQ.