Open Book Questions Highlighted1

Open Book Questions.  These are some of the ones I wrote in my Body Body of Knowledge. 1.)What is the minimum calculated thickness of a B31.3 piping system given the following data? Design Pressure

600Psig

Design temperature

650°F

Max Al Allowable Stress

19000 Psi

Pipe Size

NSP 12

 Joint Efficiency t=

PD

1.0 _ 

2(SEW+PY)

t=

600 60 0 x 12.7 12 .75 5

_ 

2[(19000 x 1) + (600 x .4)]

t= 7650 38480

t= .199”

2) During the inspection of an NPS 4, A-53 Gr. B, Type S pipe, the thickness is determined to be .180”. The system operates at 1000psi and 500°F. What is the actual remaining corrosion allowance of this pipe based on internal pressure only?

t=

PD

_ 

2(SEW + PY)

t=

1000 10 00 x 4.5 2[(18900 x 1) + (1000 x .4)]

_ 

t=

4500

_ 

38600

t= .166”

RCA = .180 - .166 = .064

Note: Find (18900) under TABLE A-1

3.) What is the most cost effective pipe schedule for the following pipe systems? Pipe Size

10 NPS

Design Pressure

400 psi at 600°F

Corrosion Allowance

0.125”

Pipe Material

ASTM A53 gr. B, Electric Resistance weld

 T=

PD

_

= schedule 30

2(SE + PY)

First find Min thickness  T=

400 x 10.75

_ 

2[(17300 x .85) + (400 x .4)

 T= 0.144”

 Then Add corrosion Allowance

+ 0.125”

.269

4) What is the nominal plate thickness required for a permanent blank made from a36 material for a flanged connection with a design pressure of 300 psi at 400°F. The blank will have a corrosion allowance of 0.125” and a gasket inside diameter of  12.5”.

 Tm= 12.5 3 x 300 in Square root symbol) 16 x 16900 x 1

_

+ .125” --------------------- (Cant figure out how to put

tm= 12.5

tm= .7175 + .125 = .842”

Look up S in TABLE A-1

5.) What is the minimum acceptable flange class rating for a piping system designed for 500 psig at a design temperature of 900°F. The flange material is ASTM A-182 Gr F2? First look up material using TABLE 1A (p4) and find A-182 Gr F2 -coordinate with Pressure-Temperature Rating TABLE (Annex )

F2- 1.7 -check Top for correct table (should have same material) Move across 900°F Row until you reach# above 500 psi Answer is class 400

6.) An NPS 12(DN 300) carbon steel standards wall pipe in Class 2 service, designed to operate at 450psig and 500°F with an allowable stress of 20000psi, has a thickness at inspection of .280 inch. What is the maximum interval for the next thickness measurement inspection if no RBI analysis has been performed?  Joint Efficiency = 1.0 ; corrosion rate = 0.025”  T=

PD

_ 

2(SE+PY)

 T=

450 x 12.750

_ 

2[(20000 x 1.0) + (450 x .4)

 T= 5737.5 40360

 T=.142”

.280 - .142 = .138”

CR= 0.025” x 2 = .05

.05

= 2.76 Years

Example in API 570 7.5 (P47) 7.) MAWP = 2Set _  D

t=

t= .32 – 2(.01 x 5)= .22

MAWP = 2SEt D

MAWP = 2(20000 x 1.0 x. 22) 16”

MAWP = 550 psig

8.) An older section of pipe of unknown material was inspected and found to have a thickness of 0.189”. The pipe is NPS 8 and appeared to originally be standard wall thickness. The system operates at 300°F. What is the current maximum allowable working pressure? Note: for unknown material use B31.3 Appendix TABLE A-1B and use the lowest E# which is (.6) which will be API 5l Furnace Butt Weld. Then Use TABLE A-1 to find allowable stress at 300°F = 14500

P= 2SEt D =2(14500)(.6)(.189)

8.625

=381 psi