API 5L X65 PSL2 Pipe

API 5L X65 pipe is a high-strength line pipe grade with a minimum yield strength of 448 MPa (65,000 psi) and a minimum tensile strength of 531 MPa (77,000 psi). It is specified under API 5L / ISO 3183, where the equivalent ISO designation is L450, and is normally supplied in PSL2.

Download API 5L X65 PSL2 Pipe data sheet (PDF) One-page summary of the supply range, chemistry, mechanical properties and inspection documents on this page. The standard is the governing document.

Size range and specification

• Outside diameter 1/2 inch – 48 inch (12.7 – 1219 mm); seamless normally up to 24 inch, LSAW up to 48 inch and above
• Wall thickness 3.2 – 40 mm (SCH 10 – SCH 160, or by wall thickness)
• Length SRL 5.8 m, DRL 11.8 m, 20 FT, 40 FT, or random 6 – 18 m
• Ends Plain end, beveled end, threaded with coupling
• Surface treatment Black varnish, 3PE / 3LPE, FBE, 3PP, bare
• Delivery condition As-rolled (R), normalized (N), quenched and tempered (Q), thermomechanical (M)
• Manufacturing process Hot rolled seamless, ERW, LSAW, SSAW
• Delivery standard API 5L / ISO 3183, PSL1 or PSL2

How this grade is supplied

• Inspection Inspected by the producing mill’s own inspection department, which is independent of production, against the delivery standard above. Third-party inspection — SGS, BV or TUV, or an inspector you send yourself — can be arranged at the mill or before shipment; give us the dates and the scope at the order stage.
• Certificate A mill test certificate to EN 10204 3.1 showing the heat number, the chemical composition and the mechanical results is standard on every order. EN 10204 3.2, countersigned by the inspector you nominate, is available on request.
• Documents with the goods The mill test certificate and the packing list travel with the shipment, and the heat number is traceable from cast through to the finished product.
• Packing Sea-worthy export packing: bundled by size with end protection, corrosion protection on request, stencilled with the size, grade and heat number.
• MOQ One bundle or one truckload; mixed sizes within a bundle accepted.
• Lead time Counted from order confirmation, not from the enquiry. Stock sizes 5–10 days; mill run or non-stock 3–5 weeks. The delivery window is fixed on the quotation.
• How we supply Sourced through partner mills; the producing mill is named on the quotation.

API 5L X65 chemical composition, PSL2, wall thickness up to 25.0 mm (maximum, %)

PSL2 grades are ordered with a delivery condition suffix: R (as-rolled), N (normalized), Q (quenched and tempered) or M (thermomechanical). The table gives the two conditions most often used for X65. When carbon is 0.12% or below, the CE(Pcm) limit of 0.25 applies instead of CE(IIW). PSL1 X65 has looser limits (P 0.030% max, S 0.030% max) and no carbon equivalent requirement.

Source: chemical composition requirements of API 5L / ISO 3183, Table 4 (PSL 1) and Table 5 (PSL 2). The standard is the governing document.

API 5L X65 mechanical properties

Elongation is calculated from the API 5L formula Af = C x A^0.2 / U^0.9, where A is the applicable tensile test cross-sectional area in mm2, U is the specified minimum tensile strength in MPa, and C is 1940 in metric units (625,000 in US customary units).

Source: tensile requirements of API 5L / ISO 3183, Table 7. The standard is the governing document.

What Does the X65 Designation Mean?

In API 5L the letter X followed by a number denotes the minimum yield strength expressed in thousands of pounds per square inch. X65 therefore means a minimum yield strength of 65,000 psi, which converts to 448 MPa. Under the ISO 3183 system the same grade is designated L450, where 450 is the minimum yield strength in megapascals. X65 sits in the upper middle of the standard grade range: strong enough for high-pressure transmission lines, still readily weldable in the field. That balance is why it is one of the most frequently specified grades for large-diameter gas pipelines worldwide.

PSL1 and PSL2 – Which One Applies to X65?

API 5L defines two product specification levels. PSL1 is a basic specification with a single set of tensile requirements and relatively loose limits on phosphorus and sulphur. PSL2 adds a mandatory carbon equivalent limit, tighter chemistry control (P 0.025% max, S 0.015% max), a maximum yield-to-tensile ratio of 0.93, mandatory impact testing, non-destructive examination and full heat traceability. For pipeline service X65 is almost always ordered as PSL2. PSL1 X65 remains available for designs that do not call for the tighter toughness and weldability controls, but the price difference between the two is normally small.

X65 PSL2: what the order must state

PSL2 fixes the additional requirements, but several values still come from the purchaser, not from the standard. State these on every X65 PSL2 enquiry:

• Grade and delivery condition: X65R, X65N, X65Q or X65M.
• Outside diameter, wall thickness or schedule, and length.
• End finish and surface treatment or coating.
• CVN impact test temperature, specimen orientation and acceptance energy.
• Carbon equivalent limit and method: CE(IIW) or Pcm.
• NDE scope: full-body UT, weld-seam UT or RT as applicable.
• Certificate level: EN 10204 3.1, or 3.2 with third-party countersignature.
• Quantity, destination port and Incoterms.

The CVN temperature is the item most often left off an enquiry. PSL2 makes the impact test mandatory but does not by itself set the temperature; that value comes from the design code or line specification, and the mill cannot proceed until it is given.

Seamless or Welded X65 Pipe?

X65 is produced in both seamless and welded forms. Seamless pipe is made by piercing and rolling a solid billet and is the default choice up to about 24 inch outside diameter. Above that, LSAW (longitudinally submerged arc welded) pipe formed and welded from plate takes over and is available to 48 inch and beyond, which is the normal construction range for gas transmission lines. ERW covers the smaller diameters. The grade is identical in all three forms; the choice is driven by diameter, wall thickness, delivery time and price rather than by strength. Where a specification calls for the highest integrity, seamless remains the preferred option.

Why Specify X65 Rather Than X60 or X70?

Pipeline design is a trade-off between strength, wall thickness and cost. Moving from X60 to X65 raises the allowable hoop stress by roughly 8%, which at the same line pressure permits a thinner wall and therefore less steel per kilometre. Moving up again to X70 saves a little more material but begins to demand tighter welding procedures, more preheat control and better low-temperature toughness. X65 is often the point at which the material saving is still worthwhile without making field welding difficult, which is why it is so widely specified for high-pressure gas lines. Where the line is not strength-limited, X60 or X52 will normally be cheaper.

Where X65 is not the right choice

X65 is a strong default for transmission pipe, but it is not the answer in every condition:

• Sour service: standard X65 is not a sour-service-qualified grade. Use an API 5L grade qualified to the sour-service requirements of the project, or confirm the specific Annex H / Annex K requirements before quoting.
• Service below the impact test temperature: if the design temperature falls below the CVN temperature the order requires, the grade may need a lower-strength option or a low-temperature specification instead.
• Field-heavy welding: X70 and above tighten preheat, heat input and weld procedure control. Where the job is welded extensively on site, the X60-to-X65 range is usually the more practical choice.
• Fracture-control and strain-based designs: these may require additional toughness, CTOD or dimensional controls beyond ordinary PSL2.

The decision is made by the design calculation and the welding plan, not by the grade name.

Testing and Documentation

Every X65 pipe is released with a mill test certificate showing heat number, chemical composition, tensile and yield results and impact values. PSL2 pipe also receives non-destructive examination of the weld seam on welded pipe and of the body, a hydrostatic test, and dimensional inspection. EN 10204 3.1 certification is standard, and EN 10204 3.2 certification countersigned by an independent inspector such as SGS, BV or TUV can be arranged when specified at the order stage. Third-party inspection and pre-shipment inspection are available on request.

Typical applications

• High-pressure gas transmission pipelines
• Crude oil trunk lines
• Offshore pipelines and risers
• Water transmission mains
• Deep and high-pressure service

Standards covered

• API 5L
• ISO 3183

Frequently asked questions

Where to go next

• API 5L Seamless Steel Pipe – seamless line pipe to API 5L
• API 5L LSAW Welded Steel Pipe – large diameter LSAW line pipe
• API 5L ERW Welded Steel Pipe – smaller diameter ERW line pipe
• API 5L X52 Pipe – the mid-range line pipe grade in detail
• API 5L Grade B Pipe – the low-strength line pipe grade, PSL1 and PSL2
• Steel Pipe Weight Calculator – work out the weight of any size and wall thickness
• Pipeline Transmission – line pipe for gathering and transmission
• Get a Quote – send the grade, size, quantity and destination port