Stay Bolts

Not sure what spec covers them, but here's a picture. Generally they are rods with threads on both ends to stabalize components in a boiler.

(From days when material was expensive and labor cheap?)

The only reference to stay bolts I found was on old steam engine web sites.

Somewhere in ASME §VIII, I think there are references to braced and stayed surfaces; and I'm surprised if TEMA (Tubular Exchanger Manufacturers Association) does not mention them. It has been too long since I have been closely involved with those, and I don't have copies.

Why and where you need stay bolts in shell & tube exchanger?

"What is the function, material, location and etc.." If you don't know the function of it, do not provide. You are the best person to decide about material based on fluids it is handling. Finally, if you know the function you can decide its location too.

thanks... now it came to mind it is to hold the stayed surface..when think deep enough, suddenly it makes sense...but i never see in shell and tube exchanger, maybe larger size diameter

Design of stay (stud) bolts for ASME flanges are clear at ASME code, VIII-1, Mandatory Appendix 2 "Rules for Bolted Flange Connections with Ring Type Gaskets".

• For flange & bolt design calculations: Flange & Bolt of Heat_Exchanger_Design_Calculation.

• For whole heat exchanger design calculations: Heat_Exchanger_Mechanical_Design Calculation.

Note. The TEMA code itself have mentioned in its paragraphs that you are requested to use ASME code to calculate the flanges and its stud bolts, gaskets, ... etc.

On their own, flat items such as tubesheets would not withstand pressure very well, unless made quite thick. To some extent, the mechanical attachment of tubes to tubesheet can help to resist bulging due to pressure, but this may not be enough. In such cases, stay bolts or other bracing may be required. Lyn's picture was amusing, but it did show flat surfaces being supported by stays from round structures, which resist pressure better.

This is different from bolts/studs for flange connections, although the objective of resisting pressure is the same.