SCH 40 or SCH 80? Wood preserving industry...

[misterd]

Since I do not have the guidebook for ASME B31.3, can someone tell me where to find (on the net) the Sh factor or allowable stress of material for steel pipes.

I am not familiar with all the standards and I am trying to choose between SCH 40 or 80.

Thanks

 

[fredb]

Hi,

Tensile for butt-welded steel pipe is: 40,000psi, for lap-welded it is 50,000psi.

The burst pressure P = (2T x S)/0
where:
T = wall thickness
S = tensile strength
0 = outside dia.(inches)

The working pressure for pipe is usually taken as 1/6, 1/8, or 1/10 of the burst pressure depending on the application.

Hope this helps.

 

[MJCronin]

misterd,

Did you check the FAQs listed for this particular forum ?

They seem to be very informative and well written....The formula you are interested in is contained in Section 104.1 in ASME B31.1 and B31.3.

For A53/A106 grade B steel pipe Sh = 15,000 psi to 650 F

Make sure you consider using a corrosion allowance in the calculation...... 0.0625 " is commonly used

MJC

 

[DLANDISSR]

MISTERD:
I don't know were the other information in the replies have come from but:

Per B31.3 - 1996 Table A-1 page 156&7
ASTM A53 and A106 Gr B Have a Basic Allowable Stess of 20,000PSI up to 400Deg F. At higher temperatures the stress goes down.
The formula for calculating the allowable pressure is:

T = 2PD/SE

P = PRESSURE - PSIG
D = PIPE OD - INCHES
S = BASIC ALLOWABLE STRESS
E = QUALITY FACTOR FROM TABLE A-1A OR A1B FOR A53 &
A106 SEAMLESS E=1; FOR A53 WELDED E=.85

BE SURE TO ALLOW FOR THE CORROSION ALLOWANCE USUALLY .0625&quotAND MANUFACTURING TOLLERANCE +/-12.5% ON THE WALL THICKNESS.

HOPE THIS CLARIFIES THE ISSUES.