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Dural · ready stockSS316 / SS316L stainless steel pipes to ASTM A312, 1/8" to 4"
1/8" to 4" nominal bore, seamless, in dual grade TP316/316L to ASTM A312 / ASME SA312. Supplied in 6 metre lengths, annealed and pickled, with an EN 10204 3.1 certificate. Sized on nominal bore and schedule — not on outside diameter.
What stainless steel pipe is, and when you need it
Sized on nominal bore and schedule — never on outside diameter.
Stainless steel pipe is a seamless hollow section made to ASTM A312 / ASME SA312 in dual grade TP316/316L, and it is sized by nominal bore and schedule. The nominal bore is a designation, not a measurement: a 2" pipe measures neither 2" across the bore nor 2" across the outside. What is fixed for a given nominal bore is the outside diameter; the schedule then sets the wall, and the bore moves with it.
That is exactly why a heavier schedule does not need different fittings — the OD is unchanged, so the same thread, weld prep or flange still fits. You need pipe rather than tube for threaded, welded or flanged runs, bulk fluid transfer and anything structural. The full comparison against tube, including where each one is specified, is in Pipe or tube? below, and the schedule tables are in Schedule and wall thickness.
If your drawing gives an OD in millimetres, you probably want tube. Tube is sized and toleranced on the outside diameter so that compression and twin‑ferrule fittings can grip it — see stainless steel tube. We stock both, and telling us which system your drawing uses saves a round trip.
Specification
Everything that has to be on the enquiry, in one table.
| Property | Specification |
|---|---|
| Size | 1/8" to 4" nominal bore |
| Material | TP316 / TP316L, dual grade |
| Dimensional standard | ASTM A312 · ASME SA312 |
| Length | 6 metres per length |
| Manufacture | Seamless. A312 also covers straight‑seam welded and heavily cold worked pipe |
| Finish | Annealed and pickled |
| End connection | Plain end · threaded end · bevel end |
| Certification | EN 10204 3.1 mill test certificate as standard |
ASTM A312 specifies seamless, straight‑seam welded and heavily cold worked austenitic stainless steel pipe for high temperature and general corrosive service. TP316/316L is the common grade; TP321 and TP347 are also used. Seamless pipe is made by extruding the material through a die and drawing it to size; welded pipe is rolled from flat plate and seam welded. Ours are seamless, from Dural.
Molybdenum is what makes 316 worth paying for. Adding it improves corrosion resistance markedly, particularly against crevice corrosion in chloride environments — which is why 316 rather than 304 goes into marine, chemical and coastal water service.
Buying stainless steel pipe in Malaysia
Where the stock sits, what it costs to get it to you, and how fast it moves.
Stock, delivery and ordering
- Where the stock is — our office is in Kuala Lumpur, and pipe is held in two warehouses: Johor Bahru and Singapore. Which one your order ships from depends on what is on the floor that week; either way the quoted price already covers transport, duty and tax. Addresses and direct lines are on the contact page.
- Dispatch — stock items leave the same or next working day.
- Delivery within Malaysia — 3 to 5 working days after dispatch. On an urgent stocked item, order to physical delivery can be under 3 working days — message us on WhatsApp and say it is urgent.
Exporting out of Malaysia? Add customs clearance in the destination country, which we cannot put a figure on. Payment terms and claim periods are in the FAQ.
How a pipe enquiry runs
Four things and we can price it without going back and forth:
- Nominal bore and schedule — for example 2"NB SCH40. Not the outside diameter.
- Grade — TP316 or TP316L. Our stock is dual grade, so one pipe usually satisfies either.
- End connection — plain, threaded or bevelled.
- Total metres — and whether you want 6 m mill lengths or cut lengths.
A product specialist prices it within two working hours. Not sure of the schedule? Send the OD and wall you measured and we will convert it.
Material certification and traceability
What comes with the pipe as standard, and what a mill certificate actually shows.
Our stainless steel pipe is supplied with an EN 10204 3.1 mill test certificate as standard, issued against the heat rather than against the delivery. A 3.2, countersigned by an inspector you or your client nominates, can be arranged where the contract demands it — say so before the order, because it has to be raised while the heat is still identifiable.
Note the approval block at the foot of it. The numbers are removed because they identify the mill, but the labels are left: this heat came from a works holding ISO 9001, PED and marine class approvals from BV, ABS, GL, CCS and CNNC. On classed marine or pressure work that block matters as much as the analysis. Tell us which documents the job needs when you enquire, not after the order.
Dual grade SS316/316L: what it means
Two grades certified on one pipe, and why that is worth having.
Dual grade means the pipe satisfies the composition limits of both 316 and 316L at once, so a single length answers either callout. You get the strength of standard 316 and the weld‑zone corrosion resistance of the ultra‑low carbon grade, and you do not have to hold two stocks to cover both drawings. The austenitic structure keeps its toughness right down to cryogenic temperature, and forms and welds well — which is most of why stainless is the default for piping.
| Element | SS316 | SS316L |
|---|---|---|
| Carbon (C) | 0.08 max | 0.035 max |
| Manganese (Mn) | 2.00 max | 2.00 max |
| Silicon (Si) | 1.00 max | 1.00 max |
| Phosphorus (P) | 0.045 max | 0.045 max |
| Sulphur (S) | 0.030 max | 0.030 max |
| Chromium (Cr) | 16.0 – 18.0 | 16.0 – 18.0 |
| Nickel (Ni) | 11.0 – 14.0 | 10.0 – 14.0 |
| Molybdenum (Mo) | 2.0 – 3.0 | 2.0 – 3.0 |
Composition limits for ASTM A312 dual spec SS316/316L, percent by weight. Carbon and the nickel floor are the only differences — the L is for low carbon, and it is the carbon that decides how the material behaves either side of a weld. Note the nickel range differs slightly from the A269/A213 tube figures; pipe and tube are separate standards.
Pipe or tube? They are not the same thing
The single most common reason a stainless enquiry has to go back and forth.
Tube is measured on outside diameter and wall thickness. It is made to a close tolerance, and the OD and wall together fix its working pressure. Pipe is specified by nominal pipe size and schedule — and the nominal size is neither the inside nor the outside diameter, it is just a label. There are two nominal sizing conventions in use, ANSI and JIS, each with its own chart back to a real OD.
| Pipe | Tube | |
|---|---|---|
| Size chart | Nominal pipe size (NPS) or nominal diameter (DN) | Outer diameter |
| Wall thickness | Schedule reading | Inches or millimetres, stated directly |
| Production range | Extensive — up to 80" | Narrower — up to about 5" |
| Production precision | Medium | High |
| Production process | Highly automated, efficient | Lengthier, more labour |
| Production time | Short | Longer |
| Material cost | Lower | Higher |
If you need a precise bore or a compression fitting, you want tube. If you are running a flanged or threaded line and mating to standard fittings, you want pipe. We stock both — see stainless steel tubes for the tube range in 4 mm to 60 mm OD.
Schedule, and what it does to the bore
Same nominal size, different wall — and a different pipe.
How schedule works
Schedule (SCH) is the measure of wall thickness. For a given nominal bore the outside diameter stays fixed and the schedule changes the wall — so the wall eats into the bore. Inside diameter is simply OD minus twice the wall.
Common schedules are SCH10, 40, 80, 160 and XXS. SCH40 is by far the most used; XXS (double extra strong) is the thickest available in each size.
Because the schedule sets the wall, it also sets the working pressure. Two pipes marked 2"NB are not interchangeable if the schedules differ.
Manufacturing tolerance to A312
Worth knowing before you machine to it or seal against it:
| Nominal bore | OD tolerance | Wall tolerance |
|---|---|---|
| 1/8" – 1 1/2" | +0.40 / −0.80 mm | ±12.5% |
| 2" – 4" | ±0.80 mm | ±12.5% |
| 5" – 8" | +1.60 / −0.80 mm | ±12.5% |
The ±12.5% wall tolerance is the one that catches people. On a nominally 3.68 mm wall that is a legitimate swing of roughly 0.46 mm, so design pressure calculations should work from the minimum wall, not the nominal.
Joining it: three end connections
The end can be finished to suit how the line will be installed.
Plain end
Finished as the mill supplies it. Generally used on smaller diameters, and the starting point if the end will be prepared on site.
Threaded end
A tapered thread such as NPT. The taper is what does the sealing, and it reduces the chance of a leak compared with a parallel thread. Pairs with our threaded fittings.
Bevel end
A 30° bevel on the pipe end, which is the standard preparation for butt welding. Specify this where the run is welded rather than screwed.
Say which end you want at enquiry. Bevelling is a preparation step, so it is far cheaper to have it done before the pipe ships than to do it on site with a grinder. Flanged connections use flanges with a bevel or plain end behind them.
Applications
Where ASTM A312 stainless pipe earns its place.
Chemical and petrochemical
Corrosion resistance, durability and high‑temperature strength together, which is what lets it carry corrosive substances under extreme conditions without the line becoming the weak point.
Pharmaceutical and food
Meets stringent cleanliness standards. The annealed and pickled surface is the reason — there is no scale or embedded contamination to harbour product.
Water treatment and marine
Durability in harsh service, and resistance to seawater corrosion. This is where the molybdenum in 316 does its work against chlorides.
Oil, gas and power
High pressure and high temperature service in oil and gas, aerospace and power generation. Also used as structural pipe where it has to carry load as well as fluid.
Also common in water supply systems, heating and plumbing, fabrication, and paper and pulp.
Why buy stainless steel pipe from RFS Hydraulics
Six things that decide whether a pipe order goes smoothly.
Ready stock, not ordered in
We stock across the 1/8" to 4" range in Johor Bahru and Singapore rather than buying in against your enquiry, and stock items dispatch the same or next working day. Schedule availability moves week to week, so send the size and schedule and we will confirm what is on the floor.
Dual grade as standard
Certified SS316/316L, so one pipe satisfies a 316 callout or a 316L callout. You do not have to hold two grades to cover both drawings.
3.1 certificate as standard
An EN 10204 3.1 mill test certificate comes with the pipe, with the analysis and mechanicals per heat. There is a real one on this page.
Ends prepared how you need them
Plain, threaded or bevelled — specified at enquiry and done before it ships, rather than left to a grinder on site.
The fittings and flanges as well
Pipe is rarely bought on its own. We stock flanges, forged pipe fittings, Class 150 fittings and valves to match, so the line arrives as one delivery.
Technical help before you order
Send a drawing, an isometric or a bill of materials. We will convert measured OD and wall into nominal bore and schedule rather than asking you to do it. More about RFS Hydraulics.
Delivery within Malaysia is already inside the price. See the FAQ or the terms and conditions.
Watch the pipe
Stainless steel pipe, in the warehouse.
Frequently asked questions
Twelve, from the standard through sizing and weight to delivery.
What is ASTM A312 grade stainless steel pipe?
ASTM A312 is the specification for seamless, welded and heavily cold worked austenitic stainless steel pipe used in high‑temperature and general corrosive service. ASME SA312 is the equivalent designation used inside the ASME code. Our pipe is seamless, in dual grade TP316/316L.
What is the difference between pipe and tube?
Pipe is specified by nominal bore and schedule; tube by outside diameter and wall thickness. The nominal size of a pipe is a label, not a measurement — it is neither the inside nor the outside diameter. Tube is made to a tighter tolerance and costs more; pipe covers a far wider size range. Full comparison is on this page.
What is the wall thickness of a Schedule 40 stainless steel pipe?
It depends on the nominal bore — schedule is a wall thickness series, not a single number. For a given nominal size the outside diameter is fixed and the schedule sets the wall, so the wall eats into the bore: inside diameter is OD minus twice the wall. SCH40 is the most commonly used; SCH10, 80, 160 and XXS are the other regular options, XXS being the thickest. Send us the nominal size and we will give you the exact wall.
What is dual grade SS316/316L?
Pipe that meets the composition limits of both grades at once, so one length satisfies either callout. It combines the strength of standard 316 with the weld‑zone corrosion resistance of low‑carbon 316L. Carbon is the deciding element: 0.08% max for 316, 0.035% max for 316L.
What is the difference between 304 and 316 stainless steel pipes?
SS304 and SS316 are similar in many respects, but SS316 has better corrosion resistance — markedly so in chloride‑rich environments — and slightly better mechanical properties. The reason is molybdenum, which 316 contains at 2.0–3.0% and 304 does not have at all.
Is stainless steel pipe safe for drinking water?
Yes. Stainless steel pipe does not leach harmful substances, resists corrosion and is easy to maintain, which is why it is used in potable water systems. Compliance with the relevant local standard for the installation is still the installer’s responsibility.
How is stainless steel pipe joined?
Three end preparations: plain end, threaded end (a tapered thread such as NPT, where the taper does the sealing) and bevel end (a 30° bevel for butt welding). Specify which you want at enquiry — bevelling before dispatch is far cheaper than doing it on site.
What tolerance does ASTM A312 pipe hold?
Outside diameter: +0.40 / −0.80 mm from 1/8" to 1 1/2"NB, ±0.80 mm from 2" to 4"NB, and +1.60 / −0.80 mm from 5" to 8"NB. Wall thickness is ±12.5% throughout — which is a real swing, so work pressure calculations from the minimum wall rather than the nominal.
What is the difference between ASTM A312 and ASTM A269?
A312 is a pipe standard, A269 is a tube standard — and that difference drives everything else. A312 pipe is sized by nominal bore and schedule and comes in a much wider size range; A269 tube is sized by outside diameter and wall thickness and is held to a tighter tolerance. Both cover austenitic stainless in TP316/316L. If your drawing says SCH40 it is an A312 drawing; if it gives an OD and a wall, it is A269. See stainless steel tubes for the A269 range.
Does stainless steel pipe rust?
Not in normal service. Stainless resists corrosion because chromium in the alloy forms a passive oxide layer that reforms itself when damaged — which is why a scratch does not start rust the way it does on carbon steel. It can still be attacked: chlorides are the main threat, which is exactly why SS316 with its 2–3% molybdenum is specified for marine, coastal and chemical work rather than SS304. Surface staining from embedded carbon steel particles — from a grinder or a wire brush used on mild steel — is the other common cause, and it is contamination rather than the pipe failing.
How do I work out the weight of stainless steel pipe?
kg/m = 0.02507 × wall × (OD − wall), both in mm, taking the density of SS316/316L as 7.98 g/cm³. The catch on pipe is that you need the real outside diameter, not the nominal bore — a 1 1/2"NB pipe is 48.3 mm OD. So 48.3 mm with a 3.68 mm wall works out at 4.11 kg/m, or about 24.6 kg for a 6 metre length. Send us the nominal size and schedule and we will do the conversion.
Can you supply pipe cut to length?
Yes. Standard supply is 6 metre mill lengths, and cut lengths are quoted on request. Say what lengths you need at enquiry rather than after the order — cutting before dispatch is cheaper than paying freight on full lengths and cutting on site, and it also means we can plan the cuts to minimise offcut waste across your list. Bevelled ends for butt welding are prepared at the same time.
Catalogue
Full dimension and schedule tables. Direct PDF download — no form, no email address.
Nominal sizes and schedule wall thicknesses are in the catalogue; stock and price are not, so send us the list and we will confirm both.
Related: stainless steel tubes · hydraulic steel tubes · flanges · forged pipe fittings · low pressure valves · about Dural
Send the nominal bore, the schedule and the end.
One length or a full bill of materials — priced by a product specialist within two working hours.