Regarding tubesheet material of construction for a heat exchanger. According to my company's datasheet tubes material of construction is 316L stainless steel, shell is made of SA-516 GR. 70, tubesheet is SA-266 with 3mm 316L cladding on tubeside and 3mm C.A. on shell side. Vendor in his offer provided tubesheet made entirely of 316L s.s. is this acceptable? According to my company's standards this is not allowed but when I asked nobody could answer me why. Please identify reasons why this is not acceptable. Thank you in advance.

A solid SS316L forging as tubesheet would cost much more than a CS cladded with SS316L forging as tubesheet. A possible exception (in my limited knowledge) would be a rare combination of a thin tubesheet and relatively small diameter. In which case it MAY be economical to use a sold SS 316L forging in lieu of a CS cladded with SS316L tubesheet.

What is the required tubesheet thickness in your current case i.e CS cladded with SS316L and it's diameter?

The cost difference in todays days is considerable.

Nevertheless, if you elect to use a solid SS316L tubesheet calculations have to be re-performed as thickness of the tubesheet will now differ.

You say nothing about TEMA type of heat exchanger, nevertheless it is acceptable to have full solid S.S. tubesheet especially if the vendor's price is competitive with others vendor, but some things have to be considered.
In case tubesheet is mounted between flanges it is no problem, but when the tubesheet is welded to shell made of CS material it is necessary to verify thermal stresses in the connection between tubesheet and shell due to different thermal expansion of CS and SS material.
regards,
malyl.

I would say, because of different temperatures, you always have different thermal expansions between tubesheet and shell, regardless of their materials. Clad tubesheet will have additional bending because of bimetalic effect. I think the real art is to assess whether it should be given consideration or it can be deemed negligible.
Regards

_________________
Konrad Anikiel

douk:

as malyl pointed out pl specify the TEMA designation of the heat exchanger. How many tubeside passes and what is the shell and tube side design pressure and temperature? Sheel ID? You need to give more detials in a post to enable others to get the idea more quickly.

If your channel side is multiple passes then the pass partition groove of depth around 5-6 mm will come in the cladding on tubeside and correspondingly the cladding thickness on tubeside you mentioned as "3mm 316L cladding on tubeside" by yopu will be inadequate.

As in my earlier post, the decision of cladding in lieu of using "solid" forging is GENERALLY based on economic design due to high cost and long delivery issues involved if one opts for a solid forging.

-jehan