How to Order Piping Products
Ordering piping products requires precision. An incomplete or ambiguous specification in your RFQ or purchase order leads to delays, requotes, wrong deliveries, and, in the worst case, unsafe equipment installed on your plant.
This guide covers the essential parameters you must specify when ordering each type of piping product, from pipes to valves, flanges, fittings, gaskets, and bolts.
Why Specifications Matter
Every piping product has a set of mandatory technical attributes that define it unambiguously. Missing even one attribute forces the supplier to assume; assumptions cause errors.
The real cost of incomplete specs:
- Requotes and back-and-forth: the supplier asks for clarifications, your engineer is busy, the reply takes days. The project schedule slips.
- Wrong material delivered: you ordered “stainless steel flanges” without specifying the grade. The supplier shipped A182 F304 instead of the F316L your piping class requires. The entire batch must be returned.
- Dimensional mismatch: a pipe ordered without specifying the dimensional standard (ASME B36.10 vs EN 10220) arrives with the wrong wall thickness for your schedule.
- Non-compliant products: forgetting to specify NACE MR0175 compliance for sour service means the delivered valves cannot be installed. New ones take 16 weeks.
- Safety incidents: a gasket ordered without specifying the inner ring material fails in service. A flange ordered without specifying the face finish doesn’t seal properly.
Common Ordering Mistakes
| Mistake | Consequence | How to Avoid |
|---|---|---|
| Material spec missing or incomplete | Wrong alloy, grade, or heat treatment delivered | Always specify the full ASTM/API/EN material standard and grade |
| Dimensional standard not stated | Wall thickness or OD mismatch (ASME vs EN) | State B36.10, B36.19, EN 10220, or EN 10216 explicitly |
| Size without schedule or wall thickness | Supplier guesses or quotes the cheapest option | Always pair NPS/DN with schedule, class, or exact WT |
| Valve trim not specified | Default trim may not suit your service conditions | Define seat, disc/wedge, and stem materials |
| Flange face type omitted | RF vs RTJ vs FF changes the gasket, bolting, and mating flange | Always specify face type and finish (AARH/Ra) |
| End connection not defined | Plain end vs beveled end vs threaded changes fabrication | Specify PE, BE, or threaded for every line item |
| Testing requirements missing | No hydrostatic test, no PMI, no impact test at your design temperature | List all required tests, certificates (EN 10204 3.1/3.2), and acceptance criteria |
| Coating/lining not mentioned | Bare carbon steel pipe delivered for buried service | Specify coating type, standard, and DFT |
| Quantity UOM confusion | ”10 pipes” vs “10 meters” vs “10 joints” | Use unambiguous units: pieces (pcs), meters (m), joints, sets |
Ordering Guides by Product Category
Select a product type below for the complete specification checklist, with core attributes, optional parameters, and example line items.
Pipes & Tubes
| Product | Key Standards | Guide |
|---|---|---|
| Pipes (seamless & welded) | API 5L, ASTM A106/A335/A312/A790, EN 10216/10217 | How to Order Pipes → |
Fittings
| Product | Key Standards | Guide |
|---|---|---|
| Buttweld Fittings (elbows, tees, reducers, caps) | ASME B16.9, B16.28, MSS SP-75 | How to Order BW Fittings → |
| Forged Fittings (couplings, unions, bushings, plugs, nipples) | ASME B16.11 | How to Order Forged Fittings → |
| Branch Fittings (weldolets, sockolets, threadolets, elbolets) | MSS SP-97 | How to Order Branch Fittings → |
Flanges
| Product | Key Standards | Guide |
|---|---|---|
| ASME Flanges (WN, SO, BL, SW, THD, LJ) | ASME B16.5, B16.47, B16.36 | How to Order ASME Flanges → |
| EN Flanges (type 01–13) | EN 1092-1, EN 10222 | How to Order EN Flanges → |
Valves
| Product | Key Standards | Guide |
|---|---|---|
| Gate Valves | API 600, API 602, API 603 | How to Order Gate Valves → |
| Globe Valves | API 600, API 602, BS 1873 | How to Order Globe Valves → |
| Check Valves | API 594, API 602, BS 1868 | How to Order Check Valves → |
| Ball Valves | API 6D, API 607, API 608 | How to Order Ball Valves → |
| Butterfly Valves | API 609 | How to Order Butterfly Valves → |
| Plug Valves | API 599, API 6D | How to Order Plug Valves → |
| Control Valves | IEC 60534, ISA S75 | How to Order Control Valves → |
Gaskets & Bolting
| Product | Key Standards | Guide |
|---|---|---|
| Gaskets (spiral wound, RTJ, soft, kammprofile, jacketed) | ASME B16.20, B16.21, API 6A | How to Order Gaskets → |
| Stud Bolts & Nuts | ASME B16.5 (Table 2), ASTM A193/A194/A320 | How to Order Stud Bolts → |
How to Use These Guides
Each guide provides:
- Core Attributes: the parameters that must appear in every RFQ and purchase order line item
- Optional/Special Attributes: additional parameters for specific services (sour, cryogenic, high-temperature, subsea)
- Correct vs Incorrect Line Item: real examples showing what a complete specification looks like compared to an incomplete one
- Common Pitfalls: product-specific mistakes that experienced engineers still make