Question for Tube Thickness

Gauge number for wire diameter and metal thickness increases for thinner material. Thus a number of tubes might be 22 gauge on average, with some variation, but not to go below 25 gauge. (Minor detail: it's Birmingham Wire Gauge.)

What is the exact wording of the code you are using?

Your specification called for 22 BWG average; the vendor did not comply with that. This probably would give you the right to reject the material, whether or not it meets the code.

However, this will result in inconvenience to both of you. If the tube is sufficient for the application, and meets the code, you could waive the variance.

Your specification stipulated a minimum of 25 BWG (about 0.50 mm; I don't have a table that shows this), but it didn't say what fraction of the tubes could be that thin. It appears that the vendor complies with the minimum value, but not the average value.

BWG means Birmingham Wire Gauge not British Wire Gauge, and BWG in tubes corresponding the Schedule No. in pipes.

The attached Table D-7 & D-7M is extracted from TEMA code (Tubular Exchanger Manufacturer Association) related with characteristics of tubing.

Note. For thicknesses of pipes represented in Schedule No., the Sch. 80 is larger in thickness compared with Sch. 40 and so on. Where the vice versa in BWG, where the tubes with BWG 14 are characterized by its higher thickness than that of BWG 18.

That depends on how old the reference is that he is taking the information from.

I don't remember ever seeing a specification like this, In the USA I follow our company's material handling section in our quality control manual that meets or exceeds the ASME requirements.

All pipe and tube will be clearly marked with nominal size for pipe and O.D. for tubing, material type and Grade, minimum required wall thickness for tubing or schedule for pipe and be marked with a heat number that corresponds with the heat number on the Material Test Report (MTR) and the MTR must be shipped with the order. Also all material ordered must be free of rust and pitting and be shipped with end caps installed to protect ends.

An example would be:

2.250", .160" Min wall, SA-213 grade T22. HT # MP122A33256 for tubing and

3", Sch. 80, SA-106 grade B, Ht # S02C098 for pipe

When the order arrives at the mill I perform a receiving inspection that consists of a visual inspection to determine if all markings are legible and heat numbers match with the MTR and then I measure wall thickness in ten or more areas of each tube and document these measurements on a pipe and tube receiving inspection report.

If I find any part of the order that does not comply with these requirements I generate a non compliance report and ask the vendor to replace it as well as let them know that no payment will be made on order until they do, this is a very good incentive to motivate the vendor to hopefully get on with it and not wait around with getting the replacement material delivered to the mill.