How to Order Pipes
Every pipe in your purchase order must be defined by a complete set of technical attributes. An incomplete specification, missing the schedule, the dimensional standard, or the end finish, forces the supplier to assume, and assumptions lead to wrong deliveries, project delays, and costly returns.
This checklist covers the mandatory and optional parameters you must include when ordering seamless (SMLS) and welded (ERW, SAW, LSAW, SSAW) pipes.
Core Attributes
These parameters must appear in every pipe line item on your RFQ or purchase order.
| Parameter | What to Specify | Example |
|---|---|---|
| Manufacturing method | Seamless (SMLS) or welded type (ERW, HFW, LSAW, DSAW, SSAW) | Seamless (SMLS) |
| Dimensional standard | ASME B36.10M (carbon/alloy steel), ASME B36.19M (stainless steel), EN 10220, EN 10216 (seamless), EN 10217 (welded) | ASME B36.10M |
| Nominal size | NPS (1/2” through 80”) or DN (15 through 2000) | NPS 6 (DN 150) |
| Wall thickness | Schedule number (STD, XS, XXS, Sch 5S through Sch 160) or exact WT in mm | Sch 40 (7.11 mm) |
| Material specification | Full ASTM, API, or EN standard with grade. Common specs: API 5L (Gr. B, X42, X46, X52, X56, X60, X65, X70, X80), ASTM A106 Gr. B, ASTM A335 (P5, P9, P11, P22, P91), ASTM A312 (TP304, TP304L, TP316, TP316L), ASTM A790 (UNS S31803, UNS S32750), EN 10216-2 | ASTM A106 Gr. B |
| Length | Standard length (5.8–6.1 m or 11.6–12.2 m), random length (RL), double random length (DRL), or cut-to-length (specify exact length) | RL (5.8–6.1 m) |
| End finish | Plain End (PE), Beveled End (BE) per ASME B16.25, or Threaded (THD) per ASME B1.20.1 | BE per ASME B16.25 |
Optional / Special Attributes
Include these when the service, project specification, or client requirements demand it.
| Parameter | What to Specify | When Required |
|---|---|---|
| Coating / lining | External: FBE, 3LPE, 3LPP per ISO 21809 or AWWA C213. Internal: cement lining, epoxy lining, PTFE lining. Specify DFT (dry film thickness). | Buried pipelines, offshore, corrosive service |
| Testing requirements | Hydrostatic test (standard per ASTM A530/A999). Supplementary: 100% UT or sample UT, radiographic testing (RT), PMI (positive material identification), Charpy impact test at a specific temperature (e.g., −46 °C) | High-pressure, cryogenic, critical service |
| NACE MR0175 / ISO 15156 compliance | Sour service compliance with maximum hardness 22 HRC for carbon steel, restricted chemical composition | H₂S-containing environments (oil & gas sour service) |
| Certificates | EN 10204 Type 3.1 (mill test report from manufacturer) or Type 3.2 (third-party witnessed inspection) | Always specify; 3.1 is standard, 3.2 for critical service |
| Marking | Per applicable ASTM/API standard (e.g., API 5L Sec. 11), color coding per ASME A13.1, stenciling or stamping preferences | Project-specific or client requirements |
| Heat treatment | Normalizing, stress relieving, quenching and tempering, PWHT simulation (simulated post-weld heat treatment) | High-temperature service (P11, P22, P91), thick-wall pipes |
Example Line Item
Correct:
100 joints - Seamless pipe, ASTM A106 Gr. B, ASME B36.10M, NPS 6, Sch 40, BE, RL (5.8–6.1 m), hydro tested per ASTM A530, MTR EN 10204 3.1
This line item defines: quantity and UOM, manufacturing method, material specification, dimensional standard, size, wall thickness, end finish, length, testing, and certification.
Incorrect:
100 pcs - Carbon steel pipe, 6 inch
This is missing the material grade, dimensional standard, schedule, manufacturing method, end finish, length, testing, and certification requirements. The supplier cannot quote or manufacture from this description.
Common Pitfalls
- Omitting the dimensional standard. ASME B36.10M and EN 10220 define different ODs and wall thicknesses for the same nominal size. A pipe ordered as “NPS 6 Sch 40” under ASME B36.10M has an OD of 168.3 mm and WT of 7.11 mm; the same nominal size under EN 10220 may have a different OD (e.g., 168.3 mm but paired with a WT from the EN thickness series). Always state the dimensional standard explicitly.
- Confusing schedule with pressure class. Schedule is a wall thickness designation, not a pressure rating. Two pipes with the same schedule but different materials have different allowable pressures. Specify the schedule for ordering; use design calculations for pressure validation.
- Not specifying NACE compliance for sour service. Standard ASTM A106 Gr. B pipe may exceed the 22 HRC hardness limit required by NACE MR0175/ISO 15156. If the pipe will be exposed to wet H₂S, you must state NACE compliance in the purchase order so the mill controls chemistry and hardness accordingly.
- Using ambiguous quantity units. “100 pipes” is ambiguous: does it mean 100 joints (individual pipe lengths) or 100 meters? Always specify quantity in joints (for individual lengths), meters (for total length), or tons (for bulk orders), and clarify the unit of measure.
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