Spectacle blinds Thickness

[rosalamanca]

I want to know where can i find the minimun thickness for spectacle blinds;

i use asme b16.48 but a client tells me i can make the blinds 1/2" thinner than that specifications; can i??

 

[DSB123]

rosalamanca,
Your Client may be right. It all depends on the pressure the blank has to sustain. Ask your client to "prove" that the spec plate can be 1/2" thinner. It is impossible to answer your question without knowing the pressure, temperature and material pipe sizes.If your Client is so smart ask him to put his requirement of thinner spectacle plates in writing - signed of course.

 

[Zapster]

The paper "Slip Blinds at pressures Causing Permanent Deformation" by J Taagepera and T Seipp show how b16.48 is over conservative. Unfortunately the tests and analysis are most likely for pressures that may be lower than your design.

 

[Berndt]

Assuming that the governing code is B31.3, then section 304.5.3 would give you an indication of the minimum required thickness, given a certain pressure and temperature.

 

[bcd]

B16.48 thickness were copied from an API standard. If you do a stress calculation based on material yield strength you will say the thicknesses are overly conservative. However, you need to account for creep, potential for excessive pressure, and corrosion allowance. The maximum stress should not exceed the allowable stress in the code. This should take care of matreial creep concerns. The rest you will need to address. Usually best to go with the standards. Less likely to get someone hurt and yourself in trouble.

bcd

 

[786392]

Just a little Humour,here.

Are we sure that Egg was first or Hen?

Best Regards
Qalander(Chem)

 

[MortenA]

Is it worth it getting a non std sch. blind? Are they made to specific order every time?

Best regards

Morten

 

[gerhardl]

What are the actual reason for the original question?

Space and mounting restrictions, or just trying to save money?

If space and mounting: selecting a stronger material than original will increase safety margin with thinner blinds.

If trying to save money: are you sure you actually are saving money supplying out of standard?

What are the (potential) cost of risk increase?