Pipe thickness calculation

No changes, go ahead, t = PD / 2(SE + PY) + CA

But, please take into consideration the pipe tolerance ±12.5% of pipe thickness.

Hallo Sir,

I need some help regarding how to calculate shell to shell joint thickness in wind mill towers. & how to determine the diamensions of flanges like thk, nos. o hole hole dia., neck thk, & height of neck etc. Pl. advice

Hi,

The formula you give I think is that included in paragraph 304.1.2 (3a), isn't it?

According to the last issue I have (2007) the formula has only one modification: Just change the (SE+PY) for (SEW+PY).

W is the "weld joint strength reduction factor" which appears in the 2004 issue in the 304.1.2 (3b) formula.

If no other data is available, W=1 for design temperatures less than 510ºC (950ºF) and 0,5 at 815ºC (1500ºF). Interpolate by straight line for intermediate temperatures. This definition is the same as in 2004 edition.

Good luck

Dear Friend

For pipe thickness calculation formula (t=pd/2(se+py) +C), may I know the notations for the same equation.

Dear Guest,

Please refer to the following CR4 post for more details and nomenclatures: Re: High Pressure Steam Pipe

Dear Sir

Thanks for the reply for #3.. I am a process designer.. I need to calculate the pipe thickness for such pipes which is for water flow...there the pressure varies from 3 kg/cm2 to depends, Will the same procedure can be followed to calculate the thickness or this is for only pressure piping....

My dear Guest

Yes, you can follow the same procedure, taking into consideration the type of pipe material and its allowable tensile strength S at the design temperature.

For simplicity, you can use the simple equation t = P D / 2 S E with a good accuracy.

Would anybody can tell me if the procured pipe thickness is not matching the specified thikness, what could be the possible solution to accept the pipe on taking the urgency of the work. Take the example as specified thk is SCH 80.Available is SCH 40?????????

Thanks

Calculation responsible engineering is the only who can. But I suppose them specify SCH 80 by some reason. Even in high urgency case it's unacceptable to use SCH 40 instead of SCH 80 unless an engineering judgement and change approval.

Kind regards

thanx. Can any body let me know those enginerring judgement and change management in this case? Can we compromise on Corrosion Alllowance upto 10%. Since pipe is already arrived, the mill tolerance can't be ignored while back calculating the thk.

Hi,

The engineering judgement is just applying the applicable design Code (ASME B31.X, etc). If after considering all load cases and material properties the actual pipe thickness is OK, then the only question is revise the drawings, calculations, and related document according to the Code/ Quality system requirements.

However, I really have doubts about the acceptability of such change.

Regarding the question about corrosion allowance, the situation is similar even in this case the mandatory requirement use to be the engineering design expertise. This allowance use to be calculated depending on the expected average corrosion rate of the material in the design medium. Reduce this allowance will affect directly to the expected design life of the piping system.

Kind regards

Appreciate your concern. but the client is asking the suggestive alternatives to use this pipe as an alternate to the specified pipe thk. Also, the basis on which it can't be acceptable. This is all due to ugency of the shutdown revival.

Regards

I have been stuck up with one more problem. The parameters for thk calculation is Flange rating 150# design temp 120 deg C, Max.presure at max temp is 16.9 bar.While thk calculation the values taken for pressure is the Max for class pr. as 19.6 bar and the Allowable stress is corresponding to 120 deg C, the material is A 106 Gr B

Now, the client is telling that if design pr is 19.6 bar @ 120 deg C then the flange to be selected is of Class 300.

Where is the mistake in assumption

Regards

Hi,

Just two things:

A 106 Gr B is a "pipe" material specification. Flange should be A 105 (if forged).

The couple of P/T given, converted to customary units are roughly 248 F and 248 psi.

Table 2-1.1 of ASME B16.5 states the following:

Even if you interpolate between 200 and 300 ºF, the permissible maximum working pressure should be about 245 psi. Your customer seems to want a bit wider tolerance.

Kind regards

My dear Kwetz,

Many thanks for your good efforts in that forum. My question is outside the subject title of that thread, but concerned with the method of inserting the table included at your post#13. I need to know how you make copy (from PDF file) and past to insert that table at your post. For me, it is easy to insert a table from a word file, but it is impossible to do the "normal" copy and past from a file in PDF formats.

I need to know how I can insert a figure, table or part of a page from a file in PDF formats to insert it in my posts of CR4 Threads. And many thanks in advance.

Goto <tools>, then <select & zoom>, then <snapshot tool>. You can cut any portion of pdf file

If I have to calculate Pipe thickness ,I have given spec with upto 2" pipe thickness calculated & I need to calculate the thickness of pipe sizes 3" & above,The pressure /temp rating chart given for upto 2" spec as per flange rating & asking to calculate same chart for 3"-24".Now For thickness calculation purpose what pressure & temp should be considered for calc purpose? shall we take Design max pressure & max temp from the Process line list for that partical spec.(e.g. say 300#spec lines) or shall we go with the max. pressure @ min temp OR Max Temp @ min Pressure as per P/T rating chart for flanges?

Solve for "P"

What is the "t" value on NPT threaded Pipe

using this same formula from B31.3

t = PD / 2(SEW+PY) + c

on Taper Threaded Pipes, NPT for example how would you calculate for the "P" value if you want to know the maximum pressure allowance for the material/size.

the above is arranged such that you are calculating teh Req'd Thickness for a said Pressure on the staraight pipe wall thickness, not a threaded thickness where the wall thickness is less.

e.g.; what is the maximum pressure for: 1/2" sch40 304L, ERW Pipe at 300F

t = wall thickness at tapered end, bottom of thread (H height of thread) - "c" (c = 0)

D = 0.840

S = 16,700 per Table A-1, ASME B31.3-2008

E = 0.8 per Table A-1B ASME B31.3-2008 for A312 Single Butt Seam Pipe

W = 1

Y = 0.4 for Austenitic Steels Table 304.1.1 ASME B31.3-2008

Any help would be appreciated!

Dear sir,

Thanks For Your Info, Please Reffer the value Y in PDF.

Regards,

Avijit Kundu

+91-9432491215

NOW A DAYS WE ARE USING WELD JOINT REDUCTION FACTOR IN THE FORMULA

(t=pd/2(seW+py) +MILL TOLERANCE+C),