API 15LR is the API specification for low-pressure fiberglass line pipe and fittings: rigid pipe made from thermosetting resin reinforced with glass fibre, used where a corrosion-resistant line runs at modest pressure, such as water transport, re-injection, geothermal and firewater service. An API 15LR reference tells you which standard route a pipe follows. It does not, by itself, give you the pressure class of your size, the edition that applies, or the scope of the fittings on the offer. This page explains where API 15LR fits, what the CNPS product pages actually state, which ordering fields to fix in an enquiry and which inspection points to agree before manufacture.
CNPS supplies API 15LR certified fiberglass pipe. We do not publish certificate numbers, monogram details or a fixed scope limit on this page; ask for the evidence and its declared scope with your quotation. The product page that covers both the low- and high-pressure routes is API 15HR And API 15LR FRP Pipeline.
Where API 15LR fits
Answer first: API 15LR fits a surface or buried line whose duty sits in a low-pressure class and whose fluid suits a glass-reinforced thermoset system. The CNPS product page describes the API 15LR pipe as intended for low-pressure systems such as geothermal wells and water transport, and lists these uses for the combined API 15HR/15LR pipe family:
- oilfield re-injection lines and flowlines;
- geothermal brine and heat-extraction lines;
- saltwater, seawater and brackish water transport;
- wastewater and sewage systems;
- chemical and mildly corrosive fluid transport;
- storage tank connections and firewater systems.
Because that list covers both routes, it tells you the service families the pipe is offered for, not which route your line needs. The deciding inputs are your design pressure and how it cycles, your design temperature and your fluid. If those fall inside a low-pressure class that the offer can evidence for your size and joint, API 15LR is the natural route. If they do not, the line belongs on the high-pressure route covered further down.
Two boundaries keep the scope clean. API 15LR is a line pipe and fittings route, not a downhole tubing route: GRE tubing for injection wells is a separate product, shown on the API 15LR GRE Tubing page (stated diameters DN40–DN100), and its pressure rating should be confirmed per offer. And API 15LR is not a thermoplastic or spoolable route; spoolable reinforced plastic pipe follows API 15S, explained in API 15S RTP: What the Spec Covers, What a Certificate Proves, and How to Ask for It in an RFQ.
What the CNPS API 15LR page states, and what it leaves open
Read the product page as a family envelope. These are the values it states today, and how to use each one in an enquiry:
| Field | What the live page states | How to read it |
|---|---|---|
| Low-pressure standards named | API 15LR (2001 + Errata 2018/2021), GB/T 21238-2007 | State which edition and errata govern your contract, and whether the national standard also applies |
| Diameter range | DN40–DN600, stated for the combined family | Confirm that each size you need is offered on the low-pressure route |
| Pressure rating | 3.45–34.5 MPa, stated for the combined API 15HR/15LR family | Not an API 15LR rating; no separate low-pressure class is stated, so ask for the class per size |
| Temperature wording | “API-rate 93 °C–110 °C”, higher temperatures on request | Give your design temperature and ask for the rating at that temperature |
| Construction | Glass fibre reinforced epoxy resin, filament wound | Confirm the resin system and process on the offered item |
The practical rule: the page fixes the standard family and the construction, while the rating of your line item comes from the offer and its evidence. Older copy on this page gave a single pressure ceiling for API 15LR pipe; we have removed it, because a single figure does not describe every edition, size or temperature. The contracted edition sets the scope, and the offer sets the class.
API 15LR pipe and fittings as one system
A low-pressure fiberglass line pipe is only as reliable as its fittings and joints. API 15LR addresses fittings alongside the pipe, so an offer should show the line as one system rather than pipe plus loose components:
- Same rating basis. Elbows, tees, reducers, couplings, flanges and adapters should carry a rating on the same basis and at the same temperature as the pipe they join.
- Same resin and joint family. Fittings should match the pipe resin system and the joint type (adhesive bell-and-spigot, threaded or flanged). For how those joint families differ in assembly and testing, see Bell-and-Spigot vs Threaded vs Flanged Joints on FRP/GRE Oilfield Pipe.
- Named transitions. Where the line meets steel valves, pumps or tanks, the offer should name the flange or adapter at each interface and who supplies it.
- Consumables in scope. Adhesives, seals and repair kits should be listed, because they are part of the joint.
Dedicated fittings and flange guides follow later this month. Until then, list each fitting type and quantity in the enquiry so the offer has to answer for every component.
Ordering fields to put in an API 15LR RFQ
These are the fields that are specific to an API 15LR order. Some you should always state; others are optional under the standard, so they only apply if you ask for them. Written in plain language, they are:
| Ordering field | What to state | Why it matters |
|---|---|---|
| Standard and edition | API Spec 15LR, the edition and errata you require, and any national or project standard that also applies | The CNPS page cites an edition plus two errata and a national standard; the contract must fix which govern |
| Quantity and sizes | Nominal size or outside diameter, total length per size and joint length | Size drives the available pressure class |
| Pressure rating | The cyclic pressure class you need per size, and whether you also want a static rating declared | Cyclic and static ratings are different bases; ask whether the offer states a cyclic rating, a static rating or both |
| Service conditions | Design temperature, fluid and any service factor or derating you expect to agree | A class is only meaningful with its temperature and fluid |
| Manufacturing process and resin system | The process and resin you require, or “manufacturer to state” | Different constructions carry different evidence |
| Pipe ends and fittings | Joint type at each end, fitting types and quantities, flanges and adapters at steel interfaces | Keeps fittings inside the same scope as the pipe |
| Optional checks | Whether you want a cure check, declared physical properties, pipe drawings and your own inspection | These are not automatic; they must be asked for |
| Nonconforming product | How rejected items will be handled, replaced or credited | Agreeing it before manufacture avoids a dispute at delivery |
| Delivery | Required date, destination, packing and marking language | Fixes the commercial frame of the line items |
This list stays on the API 15LR-specific fields. Operating data, line lists, document packs and commercial scoring for a full FRP/GRE tender belong in your complete RFQ package. If you still need to write the line specification itself, use How to Spec GRE/FRP Line Pipe from Pressure, Temperature, and Medium.
Inspection and witness points to agree before manufacture
If you plan to inspect the pipe or witness tests yourself, or send a third-party inspector, settle the ground rules in the order rather than at the factory gate:
- Notice. Agree how much notice your inspector gives and receives before a witnessed run or test.
- Place. Inspection normally takes place at the plant before shipment; if you want it elsewhere, say so in the order.
- Access. Agree access to the production and test areas that concern your order while it is being made, without disrupting other work.
- Responsibility. Your inspection checks compliance; it does not move responsibility for compliance away from the manufacturer.
- Rejection. Agree in advance how defective items found at inspection, after acceptance or in destructive tests will be rejected and replaced.
Then list the witness points you want. A typical set for a low-pressure fiberglass line pipe order:
| Witness point | What to see or review | Record to keep |
|---|---|---|
| Raw materials | Resin and glass batch identification against the declared system | Material certificates, batch traceability |
| Cure | The cure check method and result, if you requested it | Cure test record |
| Dimensions | Diameter, wall, length and joint dimensions on sampled pieces | Dimensional report |
| Pressure test | The hydrostatic test on pipe and fittings, with pressure and hold time per the agreed plan | Signed test record per item or lot |
| Marking and release | Marking against the order, packing and loading | Release note, packing list |
For how reviewers expect the test document pack to be organised before acceptance, see FRP/GRE Pipe Testing Documents: What Third-Party Reviewers Expect Before Acceptance.
When to step up to API 15HR
If your design pressure, its cycling or your size falls outside the low-pressure class an offer can evidence, the line moves to the high-pressure fiberglass route. Do not stretch an API 15LR class to cover it, and do not substitute one route for the other without a new design and evidence review. For the route choice itself, use API 15HR vs API 15LR: How to Choose High-Pressure vs Low-Pressure Fiberglass (GRE/FRP) Line Pipe and Tubing. For how to read a high-pressure claim and the evidence behind it, see API 15HR Fiberglass Line Pipe Standard: Reading an API 15HR Claim and the Evidence to Request. A selection guide for high-pressure fiberglass line pipe follows this week.
FAQ
What does API 15LR cover?
API 15LR covers low-pressure fiberglass line pipe and fittings made with thermosetting resin and glass reinforcement, including how they are made, rated, tested, inspected and marked. The contracted edition governs.
Does CNPS supply API 15LR certified fiberglass pipe?
Yes. CNPS supplies API 15LR certified fiberglass pipe. Request the evidence and its declared scope with your quotation. Certificate numbers and monogram details are not published on this page.
What pressure rating does API 15LR pipe have?
There is no single figure. The rating is a class per size at a stated temperature, on a stated basis. Ask whether the offer states a cyclic rating, a static rating or both. The CNPS product page states 3.45–34.5 MPa for the combined API 15HR/15LR family, which is not an API 15LR rating, so ask for the low-pressure class for each size.
Which API 15LR edition does CNPS cite?
The product page names API 15LR (2001 + Errata 2018/2021) and GB/T 21238-2007. State the edition and errata your project requires in the enquiry and ask the quotation to confirm them line by line.
Are API 15LR fittings covered too?
API 15LR addresses fittings as well as pipe. Ask the offer to show that each elbow, tee, reducer, coupling, flange and adapter sits inside the same rating basis, resin system and joint family as the pipe.
Is API 15LR GRE tubing the same as API 15LR line pipe?
No. Tubing runs downhole in injection and similar wells; line pipe runs on the surface or buried. They are separate products with separate ratings, so confirm the scope of each on its own offer.
If API 15LR fiberglass pipe is on your shortlist and you need an offer checked against a real line, Talk to an Engineer with the ordering fields above filled in. Bring the edition you require, the sizes and joint types, the design pressure and temperature, the fluid, the fittings list and the witness points you plan to attend.
