Seamless versus seamed tubing

[namartin]

Can someone please tell what the differences are between seamless and seamed tubing? What I mean is are there applications where one type will work better than the other? Are pressure ratings different? Does anyone know of any technical articles or websites that deal with this? Thanks for any help.

 

[saxon]

namartin, The identfications seamless or welded/seamed identfiy the manu'f. methods of the product. Seamless is pierced and swaged, where as welded, is rolled and the seam is then welded. There are differences in the pressure and temprature ratings of the two types. Sort of like the difference between copper and aluminm wire. Go to the following site:

http://www.swagelok.com

it'll cover everything.

Hope this helps.
saxon

 

[davefitz]

The ASME code section II lists the different fabrication spec requirements between seamless vs welded and the small print notes define the circumstances and limitations of each type.

Each vendor of each type of equipment has his own guidelines as to when they would risk using welded tubes. Generally mfrs have a 1 yr warrantly ,and will not use welded tubes if there is a risk of failure in the first year. From a user standpoint, the long term availability and the realtime cost of an outage due to a tube failure vs the first cost savings needs to be considered.

 

[hiliter]

There is a publication from Dupont titled:

"Welded or Seamless Heat Exchanger Tubes, That is the Question" by Mike James.

This talks about the difference and the pros and cons of each.

You can get this off of thier website.

 

[1969grad]

It is generally cost driven.

Seamless is generally used for small diameters.

Welded pipe such as ERW or DSAW are used for larger diameter piping. ERW is generally cheaper but had a bad reputation in the past. Most senior metallurgist think that DSAW is better.

 

[kenvlach]

Seamless tubing is generally considered superior in terms of corrosion resistance, mechanical properties and smoother interior surface. The latter factor is especially important where high purity is involved, as in semiconductor and pharmaceutical industries (where electropolished tubing and fittings are commonly supplied, see for example

http://www.valex.com/html/2_con.asp?page=specs)

or in high-end heat exchangers, to reduce deposition.

Re the paper "WELDED OR SEAMLESS HEAT EXCHANGER TUBES, THAT IS THE QUESTION" mentioned by hiliter (which I couldn’t find at Du Pont, but is available at 2 Avesta sites:

http://www.ast.avestasheffield.com/tech_support/docs/ast_techpaper_welded_or_seamless.pdf

or

http://www.asttube.com/template/Page____4683.asp):

It’s a very worthwhile read, and I agree that it is possible to cold-work and heat-treat welded pipe/tubing up to the level of seamless, and further, that one might conceivably get a bad batch of seamless. But, money talks. Enough specifiers are willing to pay a premium for seamless that it is widely used and available. And of course, seamless SS is available that meets both ASTM A213 and A269 whereas welded can only meet A269.