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Silly Basic Math question but I don't know the answer

Silly Basic Math question but I don't know the answer

Silly Basic Math question but I don't know the answer

(OP)
API 45th edition calls out a wall tolerance on page 145 table J.4

it simply states

wall tolerance + - 0,7 (0.028)t

should I do a calculation here based upon my given wall to come up with a wall tolerance? If so what is the calculation?

OR

Is it my wall + or - .028

BTW my wall is .375 and pipe diameter is 16" HFW

Thanks in advance,

-=Fred=-

Vass Pipe API Line Pipe Industry Leader

RE: Silly Basic Math question but I don't know the answer

The first number (listed) is in mm. The second is in inches.

I believe the answer is 0.028 times WT

RE: Silly Basic Math question but I don't know the answer

Not for HFW pipe; the SMLS pipe tolerance shows what would have been written if there was a calculation to be done in the second and third rows, compared with the first row:



However, the HFW pipe section shows no inclusion of the pipe wall thickness, so it's an absolute tolerance:

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Silly Basic Math question but I don't know the answer


API SPECIFICATION 5L (45th edition) page 145 table J.4 I think self explanatory.




Tolerances defined as a percentage of t ( t is specified wall thick.) ,for SMLS pipe having wall thickness t > 4mm or 0.157 in.
Pls look to the notes a,b,c,d for additional restrictions.

RE: Silly Basic Math question but I don't know the answer

The OP clearly states he has HFW pipe.

Those tolerances are absolute numbers not percent of t.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Silly Basic Math question but I don't know the answer

Quote (LittleInch
The OP clearly states he has HFW pipe.

Those tolerances are absolute numbers not percent of t.)


if the tolerance defined with ( say + 0,15 t ) , it is clear that 15% of t or , 0.15*t ..

RE: Silly Basic Math question but I don't know the answer

Yes, but as quoted, t convention is only given for SMLS. He has HFE, so those are absolute.

Dont fight about it. The answer is more than clear.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.

RE: Silly Basic Math question but I don't know the answer

(OP)
First off I apologize, I stated 45th ed. read wall tolerance + - 0,7 (0.028)t

When in fact 45th ed. did NOT have a t for HFW pipe.

So given the response above... that being absolute ... .236 to .591 wall would carry a tolerance of + or - .028

ie; .236 would calculate to + or - 11.8%
.591 would calculate to + or - .047% Yes Less than 1/2 of 1%

Generally tolerances are in the 12% range on all wall based upon API History.

In my opinion these tolerances do not seem correct and that is the reason I wrote the question.

Any Further dissertation would be appreciated.

Thanks in advance,

-=Fred=-

Vass Pipe API Line Pipe Industry Leader

RE: Silly Basic Math question but I don't know the answer

Welded pipe made from plate you can nowadays get very accurate wall thickness.

I've seen tolerances on welded pipe at 1mm or less for the last 10 years and the mills haven't complained.

Smls less so.

Also your calculation is incorrect.

The thicker wall is 4.7%

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Silly Basic Math question but I don't know the answer

Quote:

In my opinion these tolerances do not seem correct and that is the reason I wrote the question.

How so? In the one example in the table where the SMLS tolerance is a percentage of the wall thickness, the percentage is 12.5% to 15%, which is higher than relative tolerances you calculated for HFW

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Silly Basic Math question but I don't know the answer

(OP)
Thank you everyone for clearing this matter up but it certainly isn't advantageous to a pipe distributor such as myself.

Here is the reason why ... Pipe sitting on a rack in South Houston with proper storage would last 3 to 5 years sometime 10

without the encroachment of what API terms "Surface Imperfections" and we in the industry call pitting. Once suface imperfections

do develop, the maximum permissable inperfection is then measured by the tolerance of the wall. Which was in fact the reason

behind my question to begin with. The tighter tolerances do not weigh in our favor.

Thank you,

Fred C Lake
Vass Pipe

Vass Pipe API Line Pipe Industry Leader

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