Seamless Steel Pipe Pipeline Pipe
Line pipe for oil and gas transmission with ends prepared before it leaves the mill
Specifications
Steel Pipe Schedule and Wall Thickness Explained
A schedule number is a wall thickness class, not a dimension. For a given outside diameter the schedule decides how much steel is in the wall.
A schedule number is a wall thickness class, not a dimension. For a given outside diameter the schedule decides how much steel is in the wall, which is why SCH40 pipe in one size and SCH40 in another do not share a wall figure. The seamless range here is supplied from SCH5S through SCH160 with walls from 1.65mm to 80mm, while welded pipe is ordered directly on a wall thickness in millimeters.
What a Schedule Number Controls
Outside diameter stays fixed for a nominal pipe size so that fittings flanges and threading tools keep working. The schedule then sets how much of that diameter is wall and how much is bore. Step the schedule up and the outside diameter does not move, the bore shrinks and the pressure rating rises.
That single fact solves most confusion on a pipe inquiry. A buyer asking for 4 inch pipe has named half the specification. The other half is the schedule or an explicit wall thickness.
- Outside diameter is held constant across schedules in a size
- The schedule sets the wall thickness and therefore the bore
- A heavier schedule raises pressure capability at the same outside diameter
- Fittings and flanges follow the outside diameter not the schedule
- Name the schedule or the wall in millimeters on every pipe line
The Schedule Range Held Here
Seamless steel pipe is supplied in SCH5S, SCH10S, SCH20S, SCH20, SCH30, STD, SCH40, SCH60, SCH80, SCH100, SCH140, SCH160 and XS, or customized. That covers wall thickness from 1.65mm to 80mm, with outside diameter from 1/2 inch to 48 inch or customized.
The schedules carrying an S suffix are the lighter wall series used where a thin wall is acceptable and weight or cost matters more than pressure. STD and XS are the older standard and extra strong designations and still appear on plenty of drawings, so both remain orderable by name.
- Light wall series SCH5S SCH10S and SCH20S
- Mid range SCH20 SCH30 STD SCH40 and SCH60
- Heavy wall SCH80 SCH100 SCH140 SCH160 and XS
- Wall thickness across the range 1.65mm to 80mm
- Outside diameter from 1/2 inch to 48 inch or customized
Where Welded Pipe Is Ordered on Wall Not Schedule
Welded pipe is usually quoted on an explicit wall figure because the diameter bands are set by the forming process. ERW pipe runs from 21.3mm to 660.4mm outside diameter, which is 1/2 inch to 26 inch, with wall from 1.5 to 22.2mm. LSAW pipe runs from 355.6mm to 1820mm outside diameter with wall from 5.0 to 50mm. SSAW pipe runs from 219.1mm to 3048mm, which is 8 inch to 120 inch, with wall from 4mm to 30mm.
Those bands overlap in the middle, and that overlap is where the buying decision lives. A large diameter thin wall line is a spiral welded job. A heavy wall large diameter run belongs to LSAW. A small bore water or gas line is ERW territory.
- ERW 21.3mm to 660.4mm outside diameter with wall 1.5 to 22.2mm
- LSAW 355.6mm to 1820mm outside diameter with wall 5.0 to 50mm
- SSAW 219.1mm to 3048mm outside diameter with wall 4mm to 30mm
- Seamless where the application will not accept a weld seam
- Square and rectangle sections available in both seamless and welded
Precision Tube When Schedule Is the Wrong Language
Hydraulic cylinders bearing housings and machined assemblies are not specified on schedules at all. Precision seamless steel pipe is made by cold drawing or cold rolling and its internal and external diameter can be accurate to within 0.2mm, which is what lets a part go straight into a precision fit.
It is supplied from 10mm to 500mm outside diameter with wall from 2 to 50mm in ST52, Q345B, CK20, CK45 and SAE1026, to GB/T8713-88, GB/T3639-2009, DIN2391 and EN10305. If your drawing carries a bore tolerance rather than a schedule, this is the product line to quote against.
- Outside diameter 10mm to 500mm with wall 2 to 50mm
- Internal and external diameter accurate to within 0.2mm
- Materials ST52 Q345B CK20 CK45 and SAE1026
- Standards GB/T8713-88 GB/T3639-2009 DIN2391 and EN10305
- Cold drawn or cold rolled with high surface brightness
Length End Finish and Surface Treatment
Seamless pipe is cut to 5.8m or 6m fixed, 12m fixed, or 2 to 12m random, or customized. ERW lengths run from 0.3 to 18m, LSAW from 3 to 12.5m and SSAW from 3 to 70m. Pick the length with the container and the site handling in mind rather than after the price is agreed.
End finish is part of the order too. Ends are supplied beveled above 2 inch, plain at 2 inch and below, with plastic caps, or screwed and socketed. Surface treatment options include black painted, galvanized, natural, anticorrosive 3PE coating and polyurethane foam insulation, and casing pipe adds varnish, transparent oil and epoxy coating.
- Seamless lengths 5.8m 6m 12m fixed or 2 to 12m random
- ERW 0.3 to 18m LSAW 3 to 12.5m SSAW 3 to 70m
- Bevel end above 2 inch and plain end at 2 inch and below
- Plastic caps or screwed and socket ends on request
- Black painted galvanized natural 3PE coated or foam insulated
Grades and Standards to Call Up
Line pipe is quoted in A53B, A106B and API 5L B, X42, X46, X52, X60 and X65, plus ST37.0, ST35.8, St37.2 and the Japanese STPT and STS designations. Casing pipe is quoted in H40, J55, K55, N80, L80 with 13Cr, C90, T95 and P110. Welded pipe carries ASTM A53 Gr A and Gr B, EN S275, S275JR, S355JRH and S355J2H, and GB Q195 through Q345 with the L175 to L555 line pipe grades.
Standards across the range include API 5L, ASTM A106, ASTM A53, DIN17204, DIN17440, DIN2448, JIS G3452, EN10217, EN10219, DIN 2458, BS1387, ASTM A252, GB/T3091, GB/T9711, API 5CT and GB/T 19830. Name the one your inspector works to.
- API 5L with X42 to X65 for transmission line pipe
- API 5CT and GB/T 19830 with H40 to P110 for casing
- ASTM A106 and A53 for general pressure and structural service
- EN10217 and EN10219 for European welded pipe practice
- ASTM A252 and BS 4360 grades for piling and structural sections
Testing and Certification to Request
Welded pipe here is tested with chemical component analysis, mechanical properties covering tensile strength yield strength and elongation, technical properties covering flattening bending blow and impact tests, exterior size inspection and hydrostatic test. LSAW and SSAW add X-ray testing, and SSAW adds a metallographic test and a Charpy V impact test.
The certificate to ask for is EN 10204 with the 3.1 inspection certificate. Certification available on request also covers API 5L on line pipe, and ISO9001, BV, SGS and RoHS.
- Chemical component analysis on the heat supplied
- Tensile strength yield strength and elongation reported
- Flattening bending blow and impact testing
- Hydrostatic test and exterior size inspection
- X-ray testing on submerged arc welded pipe
- EN 10204 3.1 certificate issued with the shipment
Writing the Pipe Line on Your Purchase Order
A pipe line that can be quoted without a follow up call names the outside diameter or nominal size, the schedule or wall thickness, the grade and standard, the length regime, the end finish and the surface treatment. Add the test package and the certificate and there is nothing left to assume.
Where the drawing carries a bore tolerance rather than a schedule, quote it against precision seamless tube instead and give the machining allowance you expect to remove.
- Outside diameter or nominal size
- Schedule from SCH5S to SCH160 or a wall in millimeters
- Grade and the standard it is certified against
- Fixed or random length and the maximum length your site can handle
- Bevel plain capped or threaded ends
- Surface treatment and the test package required
Referenced
Products In This Guide
ERW Welded Steel Pipe
Electric resistance welded pipe from one strip source with a full mechanical test record
Specifications
LSAW Welded Steel Pipe
Plate formed submerged arc welded pipe with a single straight seam for large bore duty
Specifications
Spiral Submerged-Arc Welded Steel Pipe
Spiral submerged arc welded pipe for large bore water lines piling and construction
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Questions On This Topic
What does SCH40 actually mean on a pipe order?
It is a wall thickness class, not a fixed dimension. For a given outside diameter the schedule sets the wall and therefore the bore. The seamless range here runs from SCH5S through SCH160 and XS, covering walls from 1.65mm to 80mm.
Which schedules do you hold in seamless pipe?
SCH5S, SCH10S, SCH20S, SCH20, SCH30, STD, SCH40, SCH60, SCH80, SCH100, SCH140, SCH160 and XS, or customized, in outside diameters from 1/2 inch to 48 inch.
When should I use SSAW instead of LSAW pipe?
Diameter and wall usually decide it. LSAW covers 355.6mm to 1820mm outside diameter with wall from 5.0 to 50mm, while SSAW covers 219.1mm to 3048mm with wall from 4mm to 30mm. Large diameter at a lighter wall is spiral welded work, heavier wall at large diameter is longitudinal.
Can you hold a bore tolerance rather than a schedule?
Yes, on precision seamless pipe. It is cold drawn or cold rolled and its internal and external diameter can be accurate to within 0.2mm, in outside diameters from 10mm to 500mm and walls from 2 to 50mm.
What lengths can be supplied?
Seamless pipe is cut at 5.8m or 6m fixed, 12m fixed, or 2 to 12m random. ERW runs 0.3 to 18m, LSAW 3 to 12.5m and SSAW 3 to 70m. Tell us how the pipe is unloaded at site and the length regime can be set around that.
How are the pipe ends supplied?
Ends are beveled above 2 inch and plain at 2 inch and below, and can be supplied with plastic caps or screwed and socketed. Say which is needed and the ends are finished before packing.
Still Deciding After Reading This
If you are still asking "What does SCH40 actually mean on a pipe order?" send us the sizes and the duty and we will answer it against your actual order.