API 17J flexible pipe selection starts with the line you need to build, not with the pipe. Unbonded flexible pipe is a strong option for many offshore flowlines, risers and jumpers, but it isn’t the answer for every subsea or topsides line, and it isn’t the same product as the spoolable pipe used onshore. An enquiry that says which line, which fluid, which pressure and temperature, which water depth and whether the line moves gets comparable offers back. “Please quote 17J flexible, 6 inch, 3 km” doesn’t.
This page helps you decide whether an API 17J unbonded flexible pipe belongs on a given offshore line and what to put in the RFQ. If you want the background on where flexible pipe is used in deepwater projects, read API 17J Flexible Pipes for Deepwater Projects. For a scope summary of the specification, see API Spec 17J (2021) Unbonded Flexible Pipe. This article covers the fit decision and the enquiry.
Who this page is for
- Subsea and pipeline engineers deciding which lines in a field layout should be flexible and which should stay rigid.
- EPC and project teams turning a field architecture into a line list that a flexible pipe supplier can price without guessing.
- Procurement engineers who need offers for the same structure, end fittings, ancillaries and documents, not per-metre prices for different designs.
What API 17J covers, and what it doesn’t
API 17J sets minimum requirements for the design, material selection, manufacture, testing, marking and packaging of unbonded flexible pipe. It applies to the assembly: a length of flexible pipe body with an end fitting on each end. The specification covers static and dynamic pipe used as flowlines, risers and jumpers, in sweet and sour production, export and injection service. The current document is API Spec 17J, Fifth Edition (May 2024); ask suppliers which edition their certificate and design are to.
The boundaries matter just as much when you write the enquiry:
- Bonded flexible pipe isn’t covered. Bonded pipe is covered by API 17K.
- Choke and kill lines aren’t covered. API 16C applies to them.
- Ancillary components such as bend stiffeners, bend restrictors and buoyancy modules aren’t part of the 17J pipe scope. API 17L1 and 17L2 deal with them, so list them as a separate item.
- Pipe with nonmetallic tensile or pressure armour wires, or structural composite layers, is outside the 17J scope.
- API 17B is the recommended practice for using flexible pipe. It’s useful guidance, but it isn’t the purchase specification.
If a line falls into one of those boundaries, a “17J” offer may not be the right answer to the question you asked.
When unbonded flexible pipe fits an offshore line
Look at each line on its own. Flexible pipe tends to be worth a serious look when one or more of these is true:
- The line moves. A riser to a floating production unit or a dynamic jumper sees continuous motion from waves and vessel offset. Unbonded flexible pipe is designed for that kind of dynamic service, and API 17J covers dynamic risers and jumpers directly.
- The route or seabed is awkward. Static flowlines that cross uneven seabed, need to follow a winding route or connect to equipment that isn’t yet in its final position can be easier with a pipe that bends, rather than with rigid spools that must be fabricated to fit.
- Offshore welding and installation time are the cost driver. Flexible pipe arrives as long lengths on a reel or carousel with end fittings already attached, so the offshore work is mostly laying and connecting. Compare that against the rigid steel option for the same line with your installation contractor.
- The fluid is corrosive to carbon steel. The polymer pressure sheath keeps the bore fluid away from the armour wires. That doesn’t make the pipe immune: CO₂, H₂S and water that permeate through the sheath into the annulus still drive the choice of armour wire material and the annulus design, so the fluid data has to be in the enquiry.
- The line may be recovered or reused. Flexible pipe can be recovered and, depending on its condition and history, reused on another project. If that matters to your field plan, say so.
Flexible pipe is usually the second choice, or not the right object at all, in these cases:
| Situation | Look at first | Why flexible pipe is secondary |
|---|---|---|
| Onshore gathering, water or injection lines | Reinforced thermoplastic pipe (API 15S) or steel | API 17J pipe is engineered for offshore duty; onshore lines usually have simpler, lower-cost options |
| Long, large-diameter static export lines on easy seabed | Rigid steel line pipe, compared in the project’s cost and installation study | Rigid pipe often competes well when the line doesn’t move and the route is simple |
| Choke and kill lines | Pipe and hose to API 16C | Outside the API 17J scope |
| Bonded hoses (for example some offloading or short jumper hoses) | Bonded flexible pipe to API 17K | Different construction and a different document |
| Pressure, temperature or bore near or past what the offered structure is qualified for | A structure the manufacturer designs and qualifies for that duty, or rigid pipe | Don’t stretch a qualification in an email |
Keep the flexible and spoolable pipe scopes separate
Several pipe families can turn up on one project, and each is its own RFQ object with its own document and acceptance checks:
- API 17J unbonded flexible pipe: metallic armour layers, a polymer pressure sheath and, in rough-bore pipe, an inner carcass. Offshore flowlines, risers and jumpers.
- API 17K bonded flexible pipe: layers bonded together into one structure. Usually shorter hoses and jumpers.
- API 15S reinforced thermoplastic pipe (RTP): spoolable plastic line pipe for onshore gathering, water and injection lines. The basics are in RTP Pipe for Oilfield Service: What Reinforced Thermoplastic Pipe Is and How to Spec It.
- Thermoplastic composite pipe (TCP): a bonded composite pipe that is sometimes offered against the same offshore lines. For how it differs from RTP, see RTP vs TCP Pipe: Key Differences.
- Rigid steel line pipe: the usual comparison for static flowlines and export lines.
Write one enquiry per family. If you want two families priced against the same line, say that it’s a comparison and send the same line data to both.
What’s inside an unbonded flexible pipe, and why the RFQ needs it
You don’t have to design the structure, but you should know which layers the offer will describe, because each one is driven by a field you send:
| Layer | What it does | Driven by |
|---|---|---|
| Carcass (rough bore only) | Interlocked metal strip that resists collapse of the pressure sheath | Gas content, rapid depressurisation, water depth |
| Internal pressure sheath | Polymer barrier that keeps the bore fluid in | Fluid chemistry and design temperature |
| Pressure armour | Interlocked wire that carries the hoop load from internal pressure | Design pressure and bore |
| Tensile armour | Helical wire layers that carry axial load and tension | Water depth, riser tension, installation loads |
| Anti-wear and insulation layers (if needed) | Reduce wear between armour layers; hold heat in the fluid | Dynamic service; flow assurance |
| Outer sheath | Protects the armour from seawater and damage | Installation method and external environment |
Two choices come up in almost every enquiry. Rough bore or smooth bore: pipe with a carcass is normally used for oil, gas and multiphase service, where gas in the fluid could collapse the pressure sheath when pressure drops; smooth-bore pipe without a carcass is common for water injection. Annulus design: gases that permeate into the space between the sheaths have to be vented and accounted for in the armour wire choice, especially in sour service. Tell the supplier your expected CO₂, H₂S and water content so they can size this properly.
Fields to lock before you choose a 17J structure
Fill these in for each line. If a value isn’t fixed yet, give a range and say so.
- Service: production, gas, water injection, gas lift, export or chemical injection.
- Fluid: oil, gas and water fractions, CO₂, H₂S, chlorides, sand, wax and any dosed chemicals such as methanol or corrosion inhibitor.
- Design pressure: design and operating pressure, shut-in pressure, test pressure and whether the line sees vacuum or rapid depressurisation.
- Design temperature: maximum and minimum, including start-up, shut-in and cooldown.
- Bore and flow: internal diameter or flow rates, and whether pigging is required.
- Water depth and route: depth at each end, route length and seabed conditions.
- Static or dynamic: for risers and jumpers, the host type, riser configuration and the environmental and vessel-motion data the designer needs.
- Interfaces: what each end connects to (subsea tree, manifold, riser base, topsides piping) and the flange or hub type.
- Design life and reuse: service life, and whether the pipe should be recoverable.
RFQ fields for an API 17J flexible pipe line
| RFQ field | What to send | Note |
|---|---|---|
| Line ID and function | Line number, from/to, service | One row per line; don’t merge lines with different duty |
| Fluid data | Composition, CO₂, H₂S, water, sand, chemicals | Drives sheath polymer, armour wire and annulus design |
| Pressure | Design, operating, shut-in and test pressure | State units and reference point |
| Temperature | Maximum and minimum design temperature | Include transients |
| Bore | Internal diameter or required flow | State pigging needs |
| Length and water depth | Route length, depth at each end | Include spare length policy if you have one |
| Static or dynamic | Flowline, riser, jumper; riser configuration | Dynamic lines need environmental and host data |
| Bore type | Rough bore or smooth bore, or ask the supplier to propose | Ask for the reason if the offer differs from your request |
| Insulation | Required, or flow-assurance targets | Only if your flow assurance study calls for it |
| End fittings | Type, flange or hub standard, material, connection to each interface | Part of the 17J assembly; state both ends |
| Ancillaries | Bend stiffeners, bend restrictors, buoyancy, clamps | Separate scope (API 17L1/17L2); say whether to include |
| Installation | Reel or carousel, vessel limits, installation contractor | Affects reel size, lengths and tension design |
| Testing and documents | Factory acceptance tests you need, design report, material certificates, API 17J certificate copies | List what must arrive before shipment |
| Delivery | Destination, packaging, required date | Note any storage period before installation |
There is no CNPS product page for API 17J flexible pipe yet, so send the line list through Request a quotation and attach your field layout and fluid data.
Certificates and documents to ask for
CNPS supplies API 17J certified flexible pipe. Ask for copies of the certificate with the offer, and check that it covers the products, sizes, pressure classes and end-fitting configuration you are asking for. Ask for the design report or design summary for the offered structure, the material certificates for the polymer and armour layers, and the factory acceptance test plan, so you can see the tests before the pipe is built rather than after.
Comparing 17J quotes
A price per metre only compares well when the offers describe the same assembly. Before you rank them, check that each offer states:
- the structure, layer by layer, and whether it is rough bore or smooth bore;
- the design pressure and temperature it is qualified for, and the fluid it was checked against;
- static or dynamic design, and the design life;
- end fittings for both ends, and the interfaces they connect to;
- which ancillaries are included and which are priced separately;
- reel or carousel, lengths and the number of mid-line connections;
- the tests and documents included, such as certificate copies, the design report and test records;
- installation support, delivery terms and lead time.
FAQ
When is API 17J flexible pipe a good fit?
When the line moves, as with risers and dynamic jumpers, or when a static flowline has an awkward route, seabed or tie-in and offshore installation time is the main cost. The fluid, pressure, temperature and water depth must sit inside what the offered structure is designed and qualified for.
What’s the difference between API 17J and API 17K?
API 17J covers unbonded flexible pipe, where the layers can move relative to each other. API 17K covers bonded flexible pipe, where the layers are bonded into one structure. They are different products and should be separate enquiries.
Does API 17J cover bend stiffeners and buoyancy?
No. Those are ancillary components and are dealt with in API 17L1 and 17L2. List them separately in your RFQ and say whether the pipe supplier should include them.
Should I ask for rough-bore or smooth-bore pipe?
Rough-bore pipe, with an inner carcass, is normally used for oil, gas and multiphase service. Smooth-bore pipe is common for water injection. If you aren’t sure, send the fluid data and ask the supplier to propose the bore type and explain why.
Can I use API 17J flexible pipe onshore?
It’s possible, but it is rarely the most economical choice. Onshore gathering, water and injection lines usually go to reinforced thermoplastic pipe or steel, which are covered by other standards and other enquiries.
What should I send to get a useful API 17J quote?
A line list with one row per line: function, from/to, fluid data, pressure, temperature, bore, length, water depth, static or dynamic service, end fittings, ancillaries, installation method, design life and the documents you need, such as API 17J certificate copies. The RFQ table above lists each field.
Talk to an engineer before the RFQ goes out
If you’re not sure which lines in your field layout should be flexible, send the layout, fluid data and pressure and temperature data to our team. We’ll tell you which lines make sense for API 17J flexible pipe and what the offer should cover. Talk to an Engineer or email sales@cnps.com.
