Body Flange Bolt Spacing

[adnan1268]

Please refer calculation of a body flange given below from PV Elite:

ASME Maximum Circumferential Spacing between Bolts per App. 2 eq. (3) [Bsmax]:
= 2a + 6t/(m + 0.5)
= 2 * 24.000 + 6 * 62.000/(2.00 + 0.5)
= 196.800 mm Maximum Bolt Spacing Exceeded !

For vessels in lethal service or when specified by the user/agent, the
maximum bolt spacing shall not exceed the value of [Bsmax]. See ASME
VIII-1 Appendix 2 paragraph 2-5(d) for more information.

In my case the heat exchanger fluid is not lethal.

Do i need to meet the spacing requirement or should i leave it as it is.

 

[D2HANDLE]

Adnan1268,

Assuming that your Heat exchanger is also required to conform to TEMA, did you check RCB-11.23??
This para provides a way to increase the bolting moments when the actual bolt spacing exceeds the maaximum recomended bolt spacing.Make sure this requirement is complied with when calculating flange moments and stresses in the PV-Elite calculation report.

Moreover, as specified in Code Par 2-5 (d), please check if the user or his designated agent (your Client or PMC or EPC Contractor) has mentioned any special restrictions regarding bolt spacing in the applicable project specifications. Also, dont forget to check out the applicable local regulations in force for the requirement on bolt spacing, if applicable.

Thanks,
D2HANDLE

 

[SnTMan]

adnan1268, note the quantity Bsc in the output. This is a multiplier on the flange moments required when minimum bolt spacing is exceeded in lethal service or when required by the user / DA. It corresponds to the TEMA para referenced by D2HANDLE.

The use of this factor meets requirement of Apx 2 for lethal service and/or user / DA requirements. The software is applying it even though it may not be required in your case.

From my experience it is often better to meet the minimum spacing just to avoid it becoming an issue at a time when it is too late to do anything about it.

But, it meets Code, it's your choice.

Regards,

Mike

On edit: Noticed your calculation is for a flat cover. This Apx 2 bolt spacing requirement does not truly apply to the cover. Note that in UG-34 eqn (2) the term Mo does not appear. However it does apply to the mating flange.

 

[adnan1268]

Thanks D2HANDLE and SnTMan for your reply.

Regards
Adnan