Calculation of blind flange thickness

For allowable design pressure, use the Pressure/Temperature tables provided by ANSI/ASME B16.5 for the selected flange material at "design temperature".

http://www.techstreet.com/cgi-bin/detail?product_id=1134125

For maximum hydrotest pressure, you can safely use 1.3 times the B16.5 pressure value at 100 deg-F.

Gasket selection is important for flange ratings 600# and above. Spiral wound gaskets are usually recommended for higher pressures.

Always use high quality bolting materials.

Other components on your piping or vessel system may limit design pressure.

Special considerations are required for high temperatures (say above 600 deg-F), low temperatures (below -20 deg-F), cyclic services, lethal services, etc.

For hydraulic test pressure, please refer to thread Calculation of Pressure Testing

Hi Abdel,

Could you please share some aspects on stored energy calcualtions and the safe distance. I know a formula from CR4 but that doesn't explains, why. The formula is stated as below.

Safe Distance = (0.15) x d x L/D^0.4 x P^0.6

where d is the internal diameter of the pipe in M

L is the length of pipe in M

D is the diameter of pipe (never mentioned inside or outside, I 've changed the notations in M

P is the test pressure in Barg

Good Luck,

Ash Bandy

Thanks, Abdel

GA's to your 4 comments.

Hi, I calculated and I keep getting negative number. Is this accurate?

Thanks

The ASME code classified the flanges into two categories, standard flanges and nonstandard flanges.

A. For standard flanges, based on the flange NPS and its rating, the code determines all the flange dimensions, thicknesses, number of holes, BCD, hole dia. and all details, and no need to proceed any calculations. Just you have to determine the design pressure and design temp., and from ASME B16.5 you can find the rating of the flange.

In the other side, to calculate the max. design pressure of any flange with a such rating, you have to select the flange material and also you have to select the design temperature. Please refer to the following site : ASME B16.5 Flanges

B. For nonstandard flanges you have to proceed a detailed calculations in accordance with ASME code, Section VIII, dIV. 1. MANDATORY APPENDIX 2 "Rules For Bolted Flange Connections With Ring Type Gaskets". The manual calculations to design a nonstandard flange shall consumes 9 pages A4 size.

C. For nonstandard blind flanges (flat unstayed circular), thickness shall not less than the thickness of flange itself. The equation of calculating the thickness of blind flange as derived from ASME code, Section VIII, Div. 1, is:

T = d [C P/S E + 1.9 W h_G/S E d³]^0.5 , for nomenclature see UG-34(c)(2) and Fig. UG-34 Sketch (j).

The manual calculations to design a blind flange shall consumes 4 pages A4.

THANK YOU VERYMUCH FOR YOUR ADVISE

thank u sir

can u calculate?

• For design of Non-Standard Flanges (integral & blind), see CR4 Thread Flange Hydro Pressure Analysis and you can download the following samples of design calculations: Flange_Design_Calculations.PDF & Blind_Flange_Design_Calculations.PDF.

I am trying to determine non-standard ASME flange thickness however it is not clear how to apply ASME Section VIII Appendix 2. Equations require a design pressure - it's not clear to me how this is determined although I'm thinking this may be from highest system design pressure at temperature.

Please get me off center on this and let me know what should be used for flange design pressure. I also considered UG-34 (3) however this is way off. Also - if you could send Flange Design Calculations.PDF and Blind Flange Design Calculations.PDF directly to john.gaska@ghtgroup.net it would be appreciated - links send me off into cyber-corruption land.

Thank you.

Does your equation apply to hydro test flanges that are typically seeing 1.5 times MAWP? If not, is there another formula?

Yes, the calculations are carried out based on ASME codes where there is a hydrostatic test not less than 1.5 MAWP per ASME Pressure Piping codes, and not less than 1.3 MAWP per ASME Pressure Vessel codes.

I understand this to mean that the hydrotest will be at 1.3 MAWP for Pressure Piping Codes and 1.5 MAWP for Pressure Vessel Codes. Our concern is do we use MAWP or 1.3 or 1.5 times MAWP in the design of the blind flanges (depending upon appropriate code) or is there sufficient factor of safety in the design when MAWP is used in the calculations?

Also, we manufacture lined slurry pumps with ductile iron outer casings and hard metal or elastomer liners, which have non standard flanges. The companion flanges (with holes in the center) we supply for the connecting piping are typically made of A36 plate (36,000 psi yield). According to the slurry pump standard (B31.11, not B31.1) we are able to design to Appendix 2 of ASME section VIII Division I which references UG23 and Section II, Subpart 1, which shows 16,600 psi allowable stress. However, the Power Piping Code (B31.1) and corresponding Appendix A derate the allowable stress by a 0.92 factor to 15,200 psi for structural quality plate with a footnote (7) indicating a limitaion of 12.7 ksi for A36 (presumably standard grade) plate. Is the difference due to usage and code requirements? That is, the 16,600 for less severe slurry pump code and the more conservative 12,700 psi for more conservative power plant applications?

Thanks very much for your help.

MJB and MW

Our concern is do we use MAWP or 1.3 or 1.5 times MAWP in the design of the blind flanges (depending upon appropriate code) or is there sufficient factor of safety in the design when MAWP is used in the calculations?

The used pressure in design of any flange, blind flange, or any component in the piping system is the the design pressure, MAWP only, not 1.3 MAWP nor 1.5 MAWP nor any thing other than 1.0 MAWP.

The used pressure in design of any flange, blind flange, or any component in the piping system is the the design pressure, MAWP only, not 1.3 MAWP nor 1.5 MAWP nor any thing other than 1.0 MAWP.

Would have to disagree using 1.0 MAWP to design a blind flange that will be subjected to a "test pressure" of 1.5 MAWP. Understand the code, but believe there should be a suitable service factor over and above 1.0 MAWP to accomodate a higher hydrostatic test pressure. Worst case, we spend alittle more money for a safer blind flange that will be used over and over again.

Could you comment on part 2 of our question? Thank-you Abdel.

"Also, we manufacture lined slurry pumps with ductile iron outer casings and hard metal or elastomer liners, which have non standard flanges. The companion flanges (with holes in the center) we supply for the connecting piping are typically made of A36 plate (36,000 psi yield). According to the slurry pump standard (B31.11, not B31.1) we are able to design to Appendix 2 of ASME section VIII Division I which references UG23 and Section II, Subpart 1, which shows 16,600 psi allowable stress. However, the Power Piping Code (B31.1) and corresponding Appendix A derate the allowable stress by a 0.92 factor to 15,200 psi for structural quality plate with a footnote (7) indicating a limitaion of 12.7 ksi for A36 (presumably standard grade) plate. Is the difference due to usage and code requirements? That is, the 16,600 for less severe slurry pump code and the more conservative 12,700 psi for more conservative power plant applications?"

Would have to disagree using 1.0 MAWP to design a blind flange that will be subjected to a "test pressure" of 1.5 MAWP.

You have the right to disagree when you are strictly aware with the rules and recommendations of different codes and standards. Again, any pressure component such as a pipe, piping component, or a vessel shall be designed at certain design pressure P_d and be tested at a test pressure P_h, where for any case or any condition, the P_h > P_d.

And, the operating pressure P_o is not allowed to reach the test pressure P_h while the component is in operation. The limit of max. operating pressure is the max. allowable working pressure MAWP which is the same as the design pressure P_d. And it is prohibited by all codes and standards to allow for P_o or P_d or MAWP to reach up the test pressure P_h.

Note. Please refer to my post #10 at that thread and download the full design calculations of a blind flange as per ASME code.

Conclusion. The only case to apply test pressure is only while testing phase. And no way to apply the value of test pressure while the vessel is in operation, where the max. limit for pressure is the MAWP or P_d. I think that is clear and enough.

Agreed. the 1.0 MAWP is the design pressure for designing a blind flange for "operation". However, as I mentioned before, we are using the flanges to hydrostatically test our pumps in the shop, where we are required to follow the Hydraulic Institute Standards that dictate a pump shall be hydrostatically tested to 1.5 MAWP for a period no less than 10 minutes. These blind flanges are intended to be used solely for this purpose and will never be used in field operation.

Therefore, we are truly designing the blind flange to meet HI's requirements. This ensures that the flanges are thick enough to accomodate the higher test pressure. Do you feel that we are misappling the ASME equation for this type of application? and do you have any comments on part 2 of our question regarding the allowable stress differences between the ASME code vs. Power Piping code (B31.1)?

hey mr Abdel. can u tell me the procedure for pressure testing a blind flange at 1500 psi??

Dear Mr. Abdel Halim,

Can you post the sample calculation one more time. the link is not available.

thanks

Does one have to buy the $600 ASME book for the nomenclature, or that available online somewhere?

Can anyone help me to calculate the blank flange thickness for pipe ID =1600mm, Steel Shell Thickness = 32mm, Working Temp = 20 to 50 Deg, Working Internal Pressure = 160 bar, 2 nos of 38mm holes at the blank flange end ?

If stiffening plates are used and welded onto the internal blank flange, what should be the blank flange thickness ?

What formula shall be used to calculate if stiffener plates are used ?

can any boby help me

when to use which type of flange innterms of pressure.?

when to use weld neck ,slip on socketweld threaded flange at what pressure limit ?

please be specific about the pressure.

Why Joint Efficientcy (E) of Flange joint = 1 ?

Thank you for your kind.