Material Options 2

[ME231]

Could you all please share some material options meeting most if not all of the following criteria:
- Comparable in strength to SA 193 material
- Suitable for clamping loads
- Preferably available in forged bar form
- Belonging to the steel family

Any and all feedback will be greatly appreciated!
Thanks!

 

[unclesyd]

There are many materials that meet your criteria it might help to select the better one if you can post the end use and operating conditions.

Based on the OP AISI 4130 or 4140 come into mind as being readily available.

 

[metengr]

Material options are rather limited depending on specific application. For example, materials used for pressure retaining capability are limited to those approved by ASME Boiler and Pressure Vessel Code, no exceptions unless you have a prior code case that has not been annulled.

If the material is for trim or non-pressure retaining applications, you can use carbon steel as long as it is proven weldable, and you have some means of identifying the material for use.

 

[ME231]

The application is for a ASME code compliant pressure retaining component. I will need an allowable stress value of around 25000psi at room temp.
SA-197 Grade B7 is more specifically the grade I'l like to compare against.
No welding required.
As I said earlier, we would like to use this material for holding clamping loads - essentially to hold two flanges together.
Thanks!

 

[ME231]

Well Fawkes, thanks for asking.
A certain inspector disallowed me from using it since according to him, "A bolting material can only take longitudinal loads, it is tested as such during the manufacturing process and is therefore unsuitable for use in clamping loads where the load might not be strictly longitudinal".
Your comments on this will be appreciated!
Thanks

 

[unclesyd]

Not to be short but, since when?
We used B7 and B16 in all sorts of configurations to all manner of possible shear and bending loads. I can't anytime where anything but these materials were considered.

Could you possibly give more details of you application.

 

[ME231]

The application calls for a clamp holding together two flanges in a pressure vessel - one flange belongs to the shell while the other to the lid.

I would certainly love to have some ammunition against his argument. However, other than experience, I do not really have a whole lot - the fact that the material is rolled and tested for longitudinal loads is quite true.

Have you ever come across a similar argument before, unclesyd?

 

[unclesyd]

No, never. I would ask the inspector to give me a little more proof that his requirement has merit. Any material you use will only be tested longitudinally even you forging. The wouln't be nickels worth of difference in the two materials within the confines of you problem. 325 structural bolting is very similar to B7, tested the same way and used in shear modes every day.

Could you post a picture or drawing of your flange arrangement?

What are your operating conditions?


It is hard to visualize any flange where a B7 or B16 bolt wouln't be satisfactory. It is also hard to visualize where hydraulic end force wouln't be governing as any other flange loads shouldn't put that much additional loads on the flange to where you would have that much effect. You can take the allowable tensile and take 62% of that value and you will have a shear strength value to use in any calculation you could require. You can get a bend of greater than 60 degrees in these fasteners with no problem.