A sanitary tube quote is only comparable if the enquiry fixes six things: the dimensional standard, the grade, the internal surface finish (Ra), the weld seam condition, the testing and documents, and the cleanliness and packaging. Leave one out and two suppliers can quote two different products at two different prices. This checklist explains what to write for each item and why.

1. Choose the dimensional standard

The standard sets the outside diameter series, wall thickness and tolerances, so it has to match the fittings, clamps and equipment already on your line.

Standard	Size system	Typical use
ASTM A270 / ASME BPE	Inch OD (e.g. 1/2″, 1″, 2″)	North American food, dairy and beverage plants; ASME BPE for bioprocessing and pharmaceutical lines
EN 10357 / DIN 11850	Metric OD	European food, dairy, brewery and chemical plants
ISO 2037	Metric OD	Food, dairy and beverage lines, common with European hygienic equipment
JIS G3447	Metric OD	Japanese and some Asian sanitary installations

The sizes are close but not interchangeable. A 2″ ASTM A270 tube and a DN 50 DIN 11850 tube do not share the same OD, so a tube from one system will not fit the fittings of another. For a detailed side-by-side comparison of ISO 2037, DIN 11850, ASTM A270 and SMS 3008, see our ISO 2037 stainless steel tubing guide.

Write in the enquiry: the standard and its edition, OD × wall thickness, and whether the tube is welded or seamless.

2. Choose the grade: 304L or 316L

Both are low-carbon austenitic grades, which limits carbide precipitation at welds. The practical difference is molybdenum:

304L is widely used for dairy, beverage and general food service where chloride levels and cleaning chemistry are moderate.
316L contains 2–3% molybdenum, which improves resistance to pitting and crevice corrosion from chlorides, salty products and more aggressive cleaning regimes. It is the usual choice for pharmaceutical, bioprocessing and high-chloride duties.

If you are unsure, state the product, the cleaning (CIP/SIP) chemicals and temperatures, and ask the supplier to confirm. Our 304 vs 316 vs 316L selection guide covers the trade-offs in more detail.

3. Specify the internal surface finish (Ra)

This is where most sanitary enquiries are incomplete. Surface roughness affects how easily product residue and bacteria are removed during cleaning, so it has to be stated as a number, not as “polished”.

Common options:

Mill or bright annealed (BA): no mechanical polishing. Suitable for many general food and utility lines.
Mechanically polished: internal Ra typically specified from ≤ 0.8 µm down to ≤ 0.4 µm.
ASME BPE SF1 (mechanically polished): Ra ≤ 0.51 µm (20 µin).
ASME BPE SF4 (electropolished): Ra ≤ 0.38 µm (15 µin). Electropolishing also removes surface peaks rather than smearing them, which is why it is used for high-purity pharmaceutical and bioprocessing lines.

The required value is normally set by the equipment builder, the process owner’s specification or the applicable hygienic design standard, not by the tube supplier. Your job is to pass it on precisely.

Write in the enquiry:

whether the Ra applies to the inside surface, the outside surface or both;
that it is a maximum value;
the finish method (mechanical polish or electropolish);
that a profilometer Ra report must accompany the shipment.

4. Define the weld seam condition (welded tube)

On welded sanitary tube, the internal weld bead is the most likely place for residue to collect. Ask for the internal bead to be planished (cold-rolled flush with the parent wall) and polished to the same finish as the rest of the bore, so that there is no step or crevice at the seam. If the line is critical, ask how the supplier inspects the seam after finishing.

5. List the testing and documents

State the documents you need before shipment, not after:

EN 10204 3.1 mill test certificate covering chemical composition and mechanical properties for each heat.
Hydrostatic and eddy-current testing. Many standards require one or the other; for sanitary and heat-exchanger service it is reasonable to ask for both.
Dimensional inspection report (OD, wall, length; coordinate measuring machine inspection where tolerances are tight).
Ra profilometer report for the finish specified in section 3.
EN 10204 3.2 certificate or third-party inspection (for example SGS, BV or TÜV) if your project or end user requires independent witnessing. This must be agreed at order stage because the inspector has to attend the tests.

6. Cleanliness and packaging

SS sanitary tubing for beverage processing

A tube that is clean at the mill can still be contaminated in transit. For sanitary tube, specify:

end caps on both ends to keep the bore clean;
individual PVC or polyethylene wrapping to protect polished surfaces;
moisture protection for sea freight;
seaworthy wooden cases, with tube lengths and bundle weights stated;
marking and labelling requirements (heat number, standard, size) so each tube can be traced to its certificate.

7. RFQ checklist: copy and paste

Standard and edition: ______ (e.g. ASTM A270, EN 10357, ISO 2037)
Welded or seamless: ______
OD × wall thickness: ______ ; length: ______ ; quantity: ______
Grade: 304L / 316L / other: ______
Internal finish and max Ra: ______ ; external finish: ______
Weld bead: planished and polished (Y/N)
Tests: hydrostatic / eddy current / both
Documents: EN 10204 3.1 / 3.2 / third-party inspection / Ra report / dimensional report
Packaging: end caps / wrapping / wooden cases / marking
Destination and Incoterm: ______

Frequently Asked Questions

What Ra should I specify for dairy tubing compared with pharmaceutical tubing? Use the value in your equipment or process specification. As a general pattern, food and dairy lines often use mechanically polished tube, while pharmaceutical and bioprocessing lines commonly specify ASME BPE finishes such as SF4 (electropolished, Ra ≤ 0.38 µm). The tube supplier should not choose the value for you.

Should I choose mechanical polishing or electropolishing? Mechanical polishing reaches a specified Ra at lower cost and suits most food and beverage service. Electropolishing is chosen when the line needs the smoothest, most cleanable bore, typically in pharmaceutical, WFI and bioprocessing systems.

Is ASME BPE the same as ASTM A270? No. ASTM A270 is a product specification for sanitary tubing. ASME BPE is a standard for bioprocessing equipment that adds requirements such as surface finish designations (SF1, SF4 and others) and tighter controls. Check which one your project documents call for.

Can ASTM A270 tube be used with DIN 11850 fittings? Generally not. The OD series differ, so the tube and fittings will not match. Choose the tube standard that matches the fittings and equipment on the line.

What documents should come with a sanitary tube shipment? At minimum an EN 10204 3.1 mill test certificate. For polished tube, also ask for the Ra report, and for critical projects a dimensional report and, if required, an EN 10204 3.2 certificate or third-party inspection report.

How TeCarve supplies sanitary tubing

TeCarve is the exclusive export arm of two manufacturing partners in Foshan and Wenzhou, China. We supply sanitary stainless steel tube to ASTM A270, ASME BPE, EN 10357, DIN 11850, ISO 2037 and JIS G3447 dimensions, in 304L and 316L, as mill finish, bright annealed, mechanically polished or electropolished tube.

Welded tube with planished and polished internal weld bead
Hydrostatic and eddy-current testing, dimensional inspection including CMM, and Ra profilometer reports
EN 10204 3.1 mill test certificate with every shipment; EN 10204 3.2 and SGS, BV or TÜV inspection arranged on request
MOQ from 100–300 kg for standard sizes, with smaller trial orders available
In-stock sizes ship in 7–10 days; custom production takes 10–25 days after deposit
Response within 24 hours at sales@tecarve.com

How to Specify Sanitary Stainless Steel Tubing: Standard, Grade, Surface Finish (Ra) and Documentation