# Seamless pipe

> Seamless carbon and stainless pipe by NPS and schedule, sourced to ASTM A106, A312 and API 5L, with the details a pipe request should carry.

URL: https://jjprojectsok.com/products/steel-structural/seamless-pipe  
Español: https://jjprojectsok.com/es/products/steel-structural/seamless-pipe  
Updated: 2026-10-16

Seamless line pipe for process, utility and pipeline service, supplied by NPS and schedule.

**In short:** Seamless line pipe for process, utility and pipeline service, supplied by NPS and schedule. JJ Projects sources it to the specification the buyer names. Typical reference, standards: ASTM A106 (carbon), A312 (stainless), API 5L (line pipe).

## Specification references

- Standards: ASTM A106 (carbon), A312 (stainless), API 5L (line pipe)
- Dimensions: ASME B36.10M (carbon and alloy), B36.19M (stainless)
- Ends: Plain end or beveled end
- Documents: Material test report on request, such as EN 10204 type 3.1

> Typical references only. The governing specification is the one on your purchase order or datasheet.

## Typical uses

- Process and utility piping in plants, refineries and offshore facilities
- Pipelines and gathering lines where API 5L line pipe is specified
- High-temperature and high-pressure lines, for example steam and hot oil
- Stainless piping for corrosive, hygienic or low-temperature service

## What to include in a request

A request with these details can be quoted without a round of questions. Send what you have and we will ask for the rest.

1. Specification and grade, for example ASTM A106 Grade B, A312 TP316L or API 5L X52
2. NPS and schedule, or the wall thickness in millimeters or inches
3. Seamless (SMLS) or welded, if the specification allows both
4. For API 5L: product specification level, PSL 1 or PSL 2, and any sour service requirement
5. End finish: plain end, beveled end, or threaded and coupled
6. Length: random lengths or fixed cut lengths, and total quantity
7. Testing and documents: hydrostatic test, non-destructive examination, impact tests and the material test report type

[Request this item](https://jjprojectsok.com/request-a-quote?item=seamless-pipe)

## Questions

### Does NPS equal the outside diameter of the pipe?

Not for smaller sizes. NPS is a nominal designation: NPS 4 pipe has an outside diameter of 4.5 in (114.3 mm). From NPS 14 upward the outside diameter in inches equals the NPS. Wall thickness then comes from the schedule.

### How is ASTM A106 different from ASTM A53?

ASTM A106 covers seamless carbon steel pipe for high-temperature service. ASTM A53 covers pipe for ordinary uses and comes in seamless or welded forms. Your piping specification says which one the line requires.

### What does the schedule control?

For a given NPS the schedule sets the wall thickness, and with it the inside diameter and the pressure the pipe can carry. The same schedule number gives different walls at different NPS, so always state both.

## Related items

- [Weld neck flange](https://jjprojectsok.com/products/steel-structural/flange-weld-neck): Forged weld neck flanges to ASME B16.5 and B16.47 in A105, A350 LF2 and A182 grades, and what a flange request needs to state to be quoted properly.
- [90° long radius elbow](https://jjprojectsok.com/products/steel-structural/elbow-90-lr): Butt-weld 90 degree long radius elbows to ASME B16.9 in ASTM A234 WPB and A403, and what a fittings request needs to be quoted, by NPS and schedule.
- [Equal tee](https://jjprojectsok.com/products/steel-structural/equal-tee): Butt-weld equal tees to ASME B16.9 in ASTM A234 WPB and A403, sized by NPS and schedule, and what to include in a request for equal tees so it can be quoted.
- [Concentric reducer](https://jjprojectsok.com/products/steel-structural/concentric-reducer): Butt-weld concentric reducers to ASME B16.9 in ASTM A234 WPB and A403, joining two pipe sizes on one centerline, with the request details needed to quote them.

## Guides

- [Pipe schedules: NPS, OD and wall thickness](https://jjprojectsok.com/knowledge/pipe-schedules-explained): NPS is a label, not a measurement. Learn how pipe schedule sets wall thickness under ASME B36.10M and B36.19M, with OD and wall tables for NPS 2, 4, 6 and 8.
- [Material test reports (MTRs) and EN 10204](https://jjprojectsok.com/knowledge/material-test-reports): What a material test report contains, how EN 10204 types 2.1, 2.2, 3.1 and 3.2 differ, what heat numbers mean, and what to check against the purchase order.
- [How to write an RFQ for industrial materials](https://jjprojectsok.com/knowledge/how-to-write-an-rfq): What an RFQ for industrial materials must specify: item, size, schedule or class, grade, standard, quantity, MTRs, inspection, packing and Incoterm.

[All steel and structural](https://jjprojectsok.com/products/steel-structural)