Hardness Limitations for SA213 TP 304 1

[ukmet]

Good Morning,

Can any one please guide me on the following queries:

1. Our hardness of the subject tube is 100 HRB but code says it should be maximum 90 HRB. Is there any acceptable range other than defined?

2. The tensile for the same sample is coming 977 Mpa. Does tensile strength increase with increase in hardness?

3. Is there any way of single tube hydrotest for heat exchangers given in ASME or TEMA?

 

[metengr]

ukmet;

1. Our hardness of the subject tube is 100 HRB but code says it should be maximum 90 HRB. Is there any acceptable range other than defined?

If the tubes were supplied under ASME SA 213, no.

2. The tensile for the same sample is coming 977 Mpa. Does tensile strength increase with increase in hardness?

Generally, yes.

3. Is there any way of single tube hydrotest for heat exchangers given in ASME or TEMA?

Not sure what you mean by single tube hydrotest. Are you implying to hydrotest a new heater for code compliance? The answer would be no. If you have a heater in service and want to verify the integrity of a single tube, you can pressure test it.

 

[SnTMan]

ukmet, individual tubes may be hydro'd using tools such as these:

http://www.airmo.com/LPHTools.html

or these:

http://estgroup.cwfc.com/productsservices/spokes/01a_htplugs.htm

Regards,

Mike

 

[ukmet]

Dear metengr,

Thank you for your guidance. Can you please highlight in short what are the possible factors which increase tensile strength on increase of hardness?

Actually our client is providing tubes for repair of his tube bundle of heat exchanger. His requirement is that each tube to be tested for leakage before fabrication and welding with tube sheet.


Thankyou sntman

 

[metengr]

ukmet;
First, there is a good correlation of hardness and tensile strength for ferrous materials. The austenitic grades of stainless, like 304, 316 and nickel base alloys also have a correlation; increase in hardness means increase in tensile strength. Conversion tables for nickel and high-nickel alloys, cartridge brass, austenitic stainless steel plate and sheet, and copper can be found in ASTM E 140.

The most dramatic increase of tensile strength for austenitic stainless steels is work hardening. I suspect, the tubes have residual work hardening if the hardness exceeds the maximum required by specification. Also, the method of hardness testing should be evaluated to ensure readings are accurate for this material. A difference between 90 and 100 can be related to testing method.

 

[SnTMan]

ukmet, tube mill can generally do the hydro, if requested.

Regards,

Mike