Steel Pipe Bends Supplier – 3D, 5D & Induction Bends

• Radius: 3D, 5D, 6D–10D or custom
• Size: 1/2–48 in
• Angle: 45°, 90°, 180° or custom
• Standard: ASME B16.49, ASME B16.9 or your drawing
• MOQ: by the piece
• Lead time: stock 5–10 days, made to order 3–5 weeks

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Steel pipe bends: radius, angle and process to your specification

A steel pipe bend is a length of pipe formed to the radius, angle and straight tangent lengths that the line needs, instead of a fitting with fixed dimensions. Mejor Steel supplies steel pipe bends and stainless steel pipe bends in 3D, 5D and 6D to 10D radius, or to a custom radius on your drawing, from 1/2 inch to 48 inch, by medium-frequency hot induction bending or by cold bending. Bends are supplied to ASME B16.49, ASME B16.9 or the customer drawing, in carbon steel A234 WPB, stainless 304 and 316, line pipe steel API 5L X42 to X70 (PSL1 or PSL2 if specified) and alloy steel P11, P22 and P91.

Bends are ordered by pipeline contractors, EPC buyers and fabricators when the line needs a longer radius than an elbow, a non-standard angle, or tangents that replace short pipe pieces.

Mejor Steel is a trading company and export agent in Anyang, Henan. The producing mill is named on the quotation, every order ships with an EN 10204 3.1 mill test certificate, and we hold the contract, the schedule and any claim.

Pipe bend supply range

The supply range is the envelope, not a promise for every combination: the size, wall, grade, radius and process are confirmed together on the quotation.

Pipe bend vs elbow: which one the line needs

Choose an elbow when a standard 1.5D or 1.0D turn fits the layout, and a bend when the radius, the angle or the tangents are set by the design.

If a standard fitting fits the layout, see our ASME B16.9 long radius elbow page for sizes and grades, and the B16.9 centre-to-end dimensions for the fixed geometry.

Bend radius options: 3D, 5D, 6D to 10D and custom

The pipe bend radius is the centreline radius, written as a multiple of the pipe diameter: a 3D bend has a radius of three diameters, a 5D bend five. 6D, 8D and 10D, or any other radius, are made where the specification or drawing calls for them.

What “D” means: nominal size or outside diameter

Practice differs. Taking D as the nominal size, a 5D bend on NPS 4 has a radius of 5 × 4 in = 508 mm; taking D as the outside diameter, 114.3 mm in ASME B36.10M, it is 572 mm. Pipe of NPS 12 and smaller has an outside diameter larger than its size number; from NPS 14 the outside diameter in inches equals the NPS, so the two bases agree.

Bend radius by pipe size (mm)

Calculated reference values: nominal basis = n × NPS × 25.4 mm; OD basis = n × ASME B36.10M outside diameter; rounded to 1 mm. The OD basis is 6% larger at NPS 12, 19% at NPS 2 and 68% at NPS 1/2. Bends are made to the radius in mm on the order; where the enquiry gives only 3D or 5D, the quotation states the mm figure used.

Send your NPS, the radius in mm and the angle, and we confirm feasibility with the mill. Send the bend list or WhatsApp it.

Arc length and the pipe needed for one bend

The pipe in the curved part is the centreline arc length: π × R × angle / 180. Add the two tangents for the finished bend; the mill states any extra set-up length on the quotation.

Worked example, NPS 12, 5D, 90°, nominal basis: R = 5 × 12 × 25.4 = 1,524 mm, so the arc length is π × 1,524 / 2 = 2,394 mm. With 500 mm tangents at each end the finished bend is 3,394 mm along the centreline, and the centre-to-end is R plus the tangent, 2,024 mm. The same bend at 45° has an arc of 1,197 mm and a centre-to-end of R × tan 22.5° plus the tangent, 1,131 mm. On the OD basis the radius is 1,619 mm and the 90° arc 2,543 mm.

3D vs 5D pipe bends: when each is specified

A 3D bend is chosen for a compact turn with a longer radius than an elbow; a 5D pipe bend is chosen where pigging, flow or erosion favour the longer radius and the space allows it. The figures below are for NPS 12 on the nominal basis.

The tighter the bend, the more the outer arc thins and the inner arc thickens, so a 3D bend may need a heavier mother pipe than a 5D pipe bend to finish at the same minimum wall. The actual thinning depends on the process and the mill; the limit is set by the governing specification.

Hot induction bending and cold bending

Induction bends suit large diameters, heavy walls and long radii; cold bending suits smaller sizes and larger radii.

Medium-frequency hot induction bending

A medium-frequency induction coil heats a narrow band all the way around the pipe. The pipe is pushed through the coil at a constant speed while a bending arm holds the radius, so the bend is formed progressively as the heated band moves along the pipe; behind the coil the formed section is cooled, by forced air, water spray or in still air, as ASME B16.49 describes the process. Because only a narrow band is hot, the process makes 3D and 5D induction bends on large, heavy-wall pipe from a single length, with tangents left at each end.

Whether heat treatment is needed after bending depends on the material and the governing specification; see heat treatment after bending.

Cold bending

The pipe is bent at ambient temperature on a bending machine. Springback and ovality are controlled by the tooling and the radius; the limits come from the governing standard or your specification.

If your specification fixes the process, state it; otherwise the quotation states it.

ASME B16.49 induction bends: what the standard controls

ASME B16.49 is the standard for carbon steel induction bends in pipeline service. It sets the checks a bend has to pass.

Scope

ASME B16.49 covers factory-made pipeline bends of carbon steel with controlled chemistry and mechanical properties, made by induction bending, with or without tangents, for transportation and distribution piping such as ASME B31.4, B31.8 and B31.11 systems. Process and power piping are outside its scope, and bends made by girth welding smaller bends together are fabrications, not B16.49 bends. If your project names ISO 15590-1 or a company bend specification, send it with the enquiry so the bends are quoted against it.

Dimensional checks on a bend

Limits are those of the edition of ASME B16.49 or the purchaser specification named on the order; the bending mill confirms them on the quotation.

Qualification bend and production tests

Under ASME B16.49, a qualification bend is made and tested to prove the bending procedure before production. Production bends are then tested as the standard and the purchaser specification require: hardness, MT, UT or RT, and impact tests where specified. State which tests you want to witness.

Materials and standards

The material follows the pipe the bend is welded into.

Carbon steel bends: A234 WPB

For carbon steel lines the bend is ordered in ASTM A234 WPB; see our page on A234 WPB chemistry and tensile requirements.

Line pipe bends: API 5L X42 to X70

Line pipe bends are made in API 5L X42 to X70 to match the line, PSL1 or PSL2 if specified, for example X52, X65 or X70 line pipe; state the PSL, because the testing differs (see PSL1 vs PSL2). Any sour service requirements go on the order. Large-diameter induction bends are usually made from LSAW mother pipe with a wall heavy enough to allow for thinning at the outer arc.

Stainless steel pipe bends: 304 and 316

Stainless steel pipe bends in 304 and 316 are bent from A312 304/316 pipe or the pipe specification you name, in 3D, 5D or custom radius. ASME B16.49 covers carbon steel only, so stainless bends are ordered to ASME B16.9 or to the drawing, with the material specification. State any solution annealing, pickling or PMI requirement.

Alloy steel bends: P11, P22 and P91

Alloy steel bends in P11, P22 and P91 are matched to the A335 chrome-moly pipe they join,. P91 pipe depends on its heat treatment for its strength, so state the post-bend heat treatment and hardness check on the enquiry.

How to order pipe bends

The radius, angle and tangents decide the bend, so a bend enquiry needs:

• pipe size: NPS or outside diameter
• wall thickness or schedule, and the minimum wall after bending if specified
• material grade and specification, with PSL1 or PSL2 for API 5L
• bend radius in mm, or 3D, 5D, 6D, 8D or 10D with the basis
• bend angle for each bend (45°, 90°, 180° or custom)
• tangent lengths A and B
• end preparation, and any coating or surface requirement
• governing standard: ASME B16.49, ASME B16.9 or your drawing
• process, if your specification fixes it: hot induction or cold bending
• NDT and testing, witness points, and 3.1 or 3.2 certificate
• quantity per item, and the destination port

If you have a drawing or a bend schedule, send that instead: it usually contains all of the above. If you do not, use our pipe bend schedule RFQ template (XLSX): one row per bend. See also how an order runs from enquiry to shipment.

Send the bend specification WhatsApp the drawing

Quality documents and inspection

• Mill test certificate: EN 10204 3.1 with every order, showing the heat number, the chemical composition and the mechanical results.
• EN 10204 3.2: available on request, countersigned by the inspector you nominate; see EN 10204 3.1 vs 3.2.
• Third-party inspection: SGS, BV or TUV, or an inspector you send yourself, at the mill or before shipment; give us the dates and the scope at the order stage. More on third-party inspection.
• The producing mill is named on the quotation, so the documents trace back to the mill that made the bend. See our quality and inspection page.

Lead time and minimum order

Bends are supplied by the piece, and mixed sizes on one order are accepted. Stock bends ship in 5 to 10 days where available. Made-to-order bends take 3 to 5 weeks after the order and the drawing are confirmed. Each item’s lead time is confirmed on the quotation.

What decides the price

There is no list price for pipe bends: each one is quoted to its size, wall, radius, angle and grade.

Frequently asked questions

Where to go next

• Pipe fittings – the full fittings range
• Butt weld elbow – LR and SR to ASME B16.9
• ASTM A234 WPB elbow – the carbon steel grade
• Alloy steel fittings
• Stainless butt weld fittings
• Pipeline pipe and fittings

Reply within one business day. Send the bend list with the quantity and the destination port. Send the specification WhatsApp the specification