Stainless Steel Pipe vs Tube: What Should You Specify?

Chapters

Each chapter opens the video at that point on YouTube.

1. 010:00Why product form changes the specification

   Stainless steel pipe and tube can look identical. But the specification language changes the enquiry. Pipe follows piping-system language: nominal size or dimension standard. Tube is usually specified by actual OD and wall. Neither word is complete: form, standard, grade and tolerances must agree. Which drawing and service condition are you matching?

2. 020:24OD, wall thickness and tube bore

   For a round tube, OD and wall control the opening inside. ID equals OD minus twice the wall. Change the wall, and the bore and fit change too. So specify dimensions, not a size nickname. Write OD, wall thickness and length. State nominal, minimum or average wall, with tolerance when needed. If the bore controls fit, say whether ID is controlled or derived. State ends, surface and the acceptance drawing.

3. 030:56What cold drawing changes

   Cold drawing is a route, not a grade or tolerance. A hollow is pulled through a die to control the finished section. Junda lists cold rolling and cold drawing, then heat treatment, pickling, straightening, cutting and inspection. The drawing must state the finished dimensions and condition. Ask what the route changes: size, condition, surface or inspection. Cold worked does not automatically mean annealed, pickled, polished or solution treated. The specification and drawing decide the order words.

4. 041:31Straight, U-bend and rectangular forms

   Tube form follows the assembly it enters. A straight tube may become cut lengths prepared for expansion or welding. A U-bend needs radius, centre distance and leg lengths from the exchanger drawing. A rectangular tube needs width, height, wall and corner radius to drawing. Junda lists U-bend and profile forms to ASTM A688 and A213. Choose the form before the catalogue photograph. Straight tube: specify section, cut length and ends. U-bend: attach the exchanger drawing and bend geometry. Rectangular profile: give width, height, wall, corners and flow dimension. A profile name alone does not define the finished part.

5. 052:17How to write the quotation line

   Inspection should answer the failure mode you are buying against. Junda publishes chemical, UT/ET, hydrostatic, mechanical, metallographic and intergranular-corrosion capability. These are available methods, not an automatic test plan. Write method, reference standard, coverage and acceptance criteria. Write the service and design basis first, if provided. State grade, form, standard and manufacturing route. Add OD, wall, basis, length, quantity and ends. Add surface, heat treatment, inspection and certificates. Ask the quote to repeat wording and mark deviations. Junda states seamless pipes are supplied with EN 10204 3.1 MTC as agreed. EN 10204 3.2 third-party inspection is available on request; quotation confirms scope. Send Junda your grade, form, dimensions and inspection requirements for review against your drawing.