API Spec 5LD is the American Petroleum Institute specification for CRA clad or lined steel line pipe — carbon-steel pipe with an internal corrosion-resistant alloy (CRA) layer, used in oil and gas pipelines where solid CRA pipe would be too expensive. This guide is written for buyers and QA engineers: what the standard covers, what you must write on the purchase order, and what to check before you accept pipe.
This is not a copy of the standard. To buy the official text, go to the API Webstore. Clause numbers below refer to API Spec 5LD, 4th Edition, so you can check each point yourself.
Supply note: Mejor Steel is an export agent. We quote API 5LD clad and lined pipe from partner mills that hold the API Monogram license for 5LD — the producing mill is named on the quotation. Mills on the Saudi Aramco approved list can be quoted for projects that require them. HIC/SSC testing of the backing steel is available when specified, and you may appoint your own third-party inspection (TPI) agency.
Mejor Steel is the export agent for the mills that make your material: one contract, one delivery date, and the mill named on the quotation. How we supply
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API 5LD at a Glance
| Item | API 5LD requirement | Clause |
|---|---|---|
| Product | Seamless or welded clad pipe; lined pipe | §1, §5 |
| Backing steel | API 5L (45th Ed.) PSL 2 only, grades X42, X46, X52, X56, X60, X65, X70, X80 and intermediate grades | §1, Table 1 |
| Sizes | NPS 25 mm (1 in.) to 2134 mm (84 in.); up to 2500 mm (100 in.) by agreement | §1 |
| CRA layer thickness | Minimum 2.5 mm (0.100 in.) unless otherwise agreed | §5.1 |
| Clad bond test | Bond shear ≥ 137.8 MPa (20,000 psi), 1 per 50 pipes; flattening test as alternate by agreement | §8.3 a |
| Lined tightness test | Gripping force measured at MPQT and 1 per 50 pipes; method and minimum by agreement | §8.3 b |
| Hydrotest | Every length; hoop stress 95 % of backing-steel SMYS (on minimum backing wall); hold ≥ 10 s | §9.3–9.4 |
| Lined pipe ends | Seal weld liner to backing unless agreed otherwise; weld overlay of ends allowed by agreement | §10.8.2, §11.3.3 |
| Marking | Per API 5L; no marking on the CRA surface; “Spec 5LD” stenciled only if fully compliant | §13 |
Current edition: 4th Edition, March 2015 (Monogram effective 3 September 2015), with Errata 1 (June 2017) and Addendum 1 (February 2024; Monogram effective 21 August 2024). Standards distributors list it as reaffirmed in 2025. API Webstore and Accuris listings checked in November 2026 show no 5th edition — if a supplier quotes one, ask for the document.
What API 5LD Covers — and What It Doesn’t
- Clad pipe (§3.1.2, §5.2.1): CRA layer metallurgically bonded to the backing — by hot roll bonding, coextrusion, weld overlay, explosion bonding or powder metallurgy. Seamless or welded.
- Lined pipe (§3.1.4): CRA liner mechanically expanded or fitted into the backing pipe (“mechanical bond”). See our guide to mechanically lined pipe.
- Not covered: solid CRA line pipe (that is API 5LC), polymer/PTFE/rubber-lined pipe (a different product family), and OCTG.
Not sure whether you need clad, lined or solid CRA? Start with our CRA clad and lined pipe selection guide.
CRA layer grades named in API 5LD
LC 1812 (316L type), LC 2205, LC 2506, LC 2242 (Alloy 825 type), LC 2262 (Alloy 625 type), UNS S31703, N08904, N10276, Alloy 31 (N08031), Alloy 59 (N06059), Alloy 254 SMO (S31254), Alloy 400 (N04400), AL6XN-type UNS N08367 and EN 1.4529 (N08926). Other grades are possible by agreement (§1). If you need a pitting index, ask for PREN or PREW on the order (§6.1).
Purchase-Order Checklist (API 5LD Table 1, in plain English)
API 5LD §4.2 requires the buyer to state these items. Missing items are the usual cause of disputes at MTC review.
Always specify: 1. Specification: API Spec 5LD (and edition/addenda if your project fixes one) 2. Quantity (m or ft) 3. Pipe type: clad or lined 4. Manufacturing process: seamless or welded 5. Backing steel grade (PSL 2) — e.g. X65 PSL2, plus any API 5L annex your project requires (sour service, offshore) 6. CRA material (UNS or LC designation) 7. Type of CRA layer (bond method) 8. Backing steel OD and nominal wall thickness 9. Minimum CRA thickness (2.5 mm unless you agree in writing to thinner) 10. Joint length 11. End finish (bevel, square, other)
State if required (these are open unless you write them): – Chemical analysis reports; PREN/PREW – Mechanical properties of CRA layer and backing; CVN shear – CRA bond test method (clad) or gripping-force method and minimum (lined) – OD tolerance applied to ID; positive wall tolerance for clad pipe – Jointers (Annex E) – NDT plan for welded clad, seamless clad or lined pipe (§11.1–11.3) – CRA continuity; repair of CRA defects – Certification (§14) – MPS (Annex B), WPS (Annex C), MPQT (Annex D), purchaser inspection (Annex F)
Project extras most buyers add: HIC/SSC testing of the backing steel, external coating (note: coating heat can reduce liner gripping force — §8.3 note), TPI agency and hold points, end protectors.
Testing and Inspection: What to Witness
| Check | Clad pipe | Lined pipe |
|---|---|---|
| Bond / tightness | Shear ≥ 137.8 MPa, 1 per 50 (§8.3) | Gripping force, MPQT + 1 per 50; acceptance by agreement |
| Body NDT | Welded: 100 % seam RT or UT, plus UT for disbond 50 mm each side of seam; clad plate UT to ASTM A578 Level C before forming; ends UT for disbond over 100 mm (§11.1). Seamless: full-length UT, shear + compression wave (§11.2) | Backing and liner inspected; inner CRA surface by electromagnetic inspection per API 5LC (§11.3.1–11.3.2) |
| Ends | — | Seal welds: VT + dye penetrant full circumference; first 10 per run and 1 in 20 thereafter radiographed (auto UT by agreement); a reject returns to 100 % until 20 good in a row (§11.3.3–11.3.4) |
| CRA thickness | Measured by UT; frequency and location by agreement (§11.4) | Same |
| Visual | CRA free of cracks and arc burns; other CRA imperfections ≤ 0.8 mm deep (§12.2) | Same |
| Hydrotest | 95 % SMYS, ≥ 10 s (§9) | Same; may be waived by agreement if the lining process already stressed the full length higher (§9.5) |
Repairs (§12.3): weld repair of the backing steel is prohibited. CRA layer repairs only by agreement. Seam repairs within 200 mm of the pipe end only by agreement. Disbonding of clad pipe is a defect; none is allowed within 100 mm of a pipe end.
Cleaning (§12.4): scale, spatter and heat-treatment residue must be removed from the CRA surface. The recommended sequence ends with a rinse in water below 200 mg/l chloride. Pipe must ship clean and dry; end protectors that keep moisture out are recommended.
Purchaser inspection (Annex F): give the mill reasonable notice to witness tests. Inspection normally takes place at the mill before shipment unless the PO says otherwise, and non-conforming pipe may be rejected even after acceptance if it proves defective in service.
Hardness Limits (API 5LD Table 7)
Many supplier pages quote a single “HRC ≤ 22” figure. API 5LD sets limits by material, in HV10:
| Material | Maximum hardness |
|---|---|
| Ferritic backing steel | 248 HV10 at all locations unless otherwise agreed |
| Austenitic stainless (e.g. LC 1812) | 300 HV10 |
| 22 % duplex (LC 2205) | 300 HV10 parent; 334 HV10 weld and HAZ |
| 25 % duplex / super duplex | 300 HV10 parent; 378 HV10 weld and HAZ |
| Nickel alloys, e.g. 825 (LC 2242), 625 (LC 2262) | 345 HV10 (explosion-welded: cold-work hardness up to 40 HRC per NACE MR0175/ISO 15156-3) |
For sour service your project may impose tighter limits through NACE MR0175/ISO 15156 — write them on the PO.
API Monogram: How to Verify a Mill
- “Spec 5LD” on the pipe means the manufacturer claims full compliance (§13.2). The API Monogram is separate and can only be applied by a licensed facility.
- Check the mill’s licence number and scope (5LD, clad and/or lined) on the API Composite List before you award. Licences expire and scopes differ.
- Addendum 1 (2024) deleted the Monogram clause in §1.2 and added a Foreword pointer to API Spec Q1 Annex A for Monogram rules.
- On our quotations the producing mill is named, so you can check its licence yourself.
Common Supplier Claims to Question
| Claim seen online | What API 5LD says |
|---|---|
| “CRA layer 1.5 mm standard” | Minimum 2.5 mm unless agreed — get the exception in writing |
| “Bond strength ≥ 140 MPa per API 5LD” | Requirement is 137.8 MPa (20,000 psi); ask for the test method and actual results |
| Backing pipe in GB/EN grades | 5LD requires API 5L PSL 2 backing |
| “HRC ≤ 22” as the hardness rule | Table 7 limits are in HV10 and differ by material (248 HV10 backing, 300–378 HV10 CRA and welds) |
| “API 5LC clad pipe” | 5LC is solid CRA line pipe; clad/lined is 5LD |
| “Lined pipe” meaning PTFE/rubber | In 5LD, lined means a CRA metal liner |
How We Quote API 5LD Pipe
Send the Table 1 items above (or your datasheet). We return: producing mill (API Monogram licensee), MPS/MPQT scope, NDT plan against §11, test frequencies, delivery date, and TPI hold points. Aramco-approved mills and HIC/SSC on request. Request a quote.
FAQ
What is API 5LD?
API Spec 5LD is the API specification for CRA clad or lined steel line pipe: carbon-steel API 5L PSL2 backing with an internal corrosion-resistant alloy layer, for oil and gas pipelines.
What is the latest edition of API 5LD?
The 4th Edition (March 2015), with Errata 1 (June 2017) and Addendum 1 (February 2024). Distributors list it as reaffirmed in 2025.
What is the difference between API 5LD and API 5LC?
API 5LC covers solid CRA line pipe. API 5LD covers carbon-steel pipe with a clad (metallurgical) or lined (mechanical) CRA layer.
What is the minimum CRA thickness in API 5LD?
2.5 mm (0.100 in.) unless the purchaser and manufacturer agree otherwise (§5.1).
What bond strength does API 5LD require for clad pipe?
A bond shear strength of at least 137.8 MPa (20,000 psi), tested on one pipe in every 50 (§8.3).
Does API 5LD set a minimum gripping force for lined pipe?
No fixed value. The measurement method and the minimum are agreed between purchaser and manufacturer, measured at MPQT and on one pipe per 50 (§8.3).
Which backing steel grades are allowed?
API 5L PSL2 grades X42 to X80, including intermediate grades. PSL1 is not covered.
What is the hydrostatic test pressure in API 5LD?
Each length is tested to a hoop stress of 95 % of the backing steel SMYS, based on its minimum wall, held for at least 10 seconds (§9).
Can I get API 5LD pipe with HIC/SSC testing and third-party inspection?
Yes. HIC/SSC testing of the backing steel can be added to the order, and you may appoint your own TPI agency.
What hardness does API 5LD allow?
Backing steel max 248 HV10 unless agreed. CRA layers range from 300 HV10 (austenitic) to 345 HV10 (nickel alloys), with higher limits in duplex welds and HAZ (Table 7).
Where can I download the API 5LD PDF?
The official text is sold by API (apiwebstore.org) and authorised distributors. We don’t share copies.
Sources and Review
Prepared by the Mejor Steel export team from the text of API Spec 5LD, 4th Edition (2015), Addendum 1 (2024), and the API Monogram update notice (27 February 2024). Clause numbers are given so engineers can check each point against their licensed copy. Project specifications (e.g. DNV-ST-F101, company specs) may override these defaults — your PO governs.
Last reviewed: November 2026.
Related
Choosing between clad, lined and solid CRA: CRA clad & lined pipe. Lined construction in depth: Mechanically lined pipe (MLP). Backing steel grades: API 5L X60 · API 5L X42.
Ordering to API 5LD? Send the Table 1 items (clad/lined, backing grade, CRA grade & thickness, OD, wall, ends, quantity, destination) — producing mill named on the quotation.
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