Pipe class 3

[santoshdada]

can any one expalin what is pipe class in MS piping,Like Class-A,Class-B,Class-C etc

is it same as schedule?? whether i need to spacify Pipe schedule with Class

thanks in advance

 

[BigInch]

Maybe someone should first explain what is MS piping.

 

[tinphattech2010]

Hi!
I think maybe Santoshdada means MS piping is piping made from mild steel pipe.
Mild steel is steel has low carbon, contains 0.16–0.29% carbon.
I have seen piping that have class A, B and C. It appears in Project Piping Specification Document. (Class 150# = Class A, Class 300# = class B, Class 600# = class C).
I also seen in Process and Instrument Diagram (P&ID), the piping is "number of pipe + B1" (B for pressure class, A for above ground).
Piping pressure class (A, B, C) is not the same with Schedule. Pipe schedule we chose after we calculate the thickness of pipe (already have pipe diameter).
Best regards!

 

[LSThill]

santoshdada (Mechanical)

REVIEW API RP 14E
APPENDIX C
EXAMPLE PIPE, VALVES AND FITTINGS TABLES

EXAMPLE C.l
EXAMPLE INDEX
PIPE, VALVES AND FITTINGS TABLES
Table Service Pressure Rating Ciassification


LEONARD STEPHEN THILL, Oil & Energy Professional

http://www.linkedin.com/in/leonardstephenthill

 

[santoshdada]

somewhere i found that as well as class changes thickness also changes thats why i confused as i know class represent tensile strength of pipe

 

[dcasto]

class is not tensil strenght of pipe. Thickness changes due to diameter and pressure rating. Yeah, tensil strenght does come in, but 90% of all the pipe used in plants has the same yield strenght and therfore it is a constant, not a variable.

 

[cloa]

You should clarify- I don't know myself- but I think you mean most pipe in plants has the same yield and tensile strength.

 

[racookpe1978]

Sr. DCasto:

"Most pipe in plant has the same yield and tensile strength" ???

Please explain what you intended with this: I most strongly disagree, unless you meant that "pipe used within the same service specification and rating/class in the same plant (or for the same company under identical conditions usually is the same material and schedule but may be different sizes".

 

[dcasto]

I've had some engineers try to claim that co-qualified pipe A106 gradeB / API 5LX46 could be rated with the yeild strenght of 46,000, but you can't do that. Look at the charts for the most common pie used, ASTM A53 and A106, its 35,000 psi. If you go the most common alloy/SS, they are 35000 psi. even the grade A and 304SS are 30,000.

So, how many 9% nickel A334 75000psi lines have you seen used?

 

[TGS4]

Selected yield and ultimate values for pipe that are in the last plant that I worked on:

Yield (ksi) | Ultimate (ksi)
SA-53-A (100°F) 30 | 48
SA-106-A (100°F) 30 | 48
SA-333-1 (100°F) 30 | 55
SA-672-L70 (100°F) 40 | 70
SA-335-P11 (100°F) 30 | 60
SA-335-P22 (100°F) 30 | 60
SA-312-TP316 (100°F) 30 | 75
SA-312-TP312N (100°F) 35 | 80
SA-312-TP321 (100°F) 25 | 70
SA-312-XM-19 (100°F) 55 | 100
SA-790-UNS32906 (100°F) 94 | 116
SB-42-UNSC10200-O61 (100°F) 9 | 30
SB-619-UNSN06022 (100°F) 45 | 100

[/sarcasm on] On yield, the variation is 25-40ksi (ignoring the outliers). OK, I can buy that a 60% variation is small. On ultimate, the variation is 48-100ksi (again, ignoring the outliers). I guess that 108% variation is small, too. [/sarcasm off]

And, don't forget that these are room temperature (up to 100°F) values. The variation as you get up into actual operating temperatures (400°F-1200°F) can be astounding, particularly when creep effects come into play.

Please DON'T use yield or ultimate when referring to the allowable stresses of piping in a process facility. These are meaningless values without context. Allowable stresses at temperature have meaning AND context.

Back to the OP, I am guessing that they are referring to the TYPE/GRADE of material. Such as SA-53, Grade A, Grade B, or SA-106, Grade A, B, and C. Whatever nomenclature you have for your piping class has likely zero relevance to the material specification or grade. It's just a name. You need to pay attention to the actual material specified in the class, AND the pressure-temperature rating in the class specification.

 

[BigInch]

TGS I think you have solved the mystery. With the A53 and A106 proper designation added, Santos' question makes perfect sense.

Santos, if you would please learn the proper names and designations for your materials, you would get your questions answered quickly and .... without causing so much confusion.

 

[santoshdada]

thx to all but my question is as it is i only asked Class#A/B/C Differences on same size as project people are purchasing pipe just mentioning Nominal bore,MOC and Class-A/B/C Only

 

[Kiwi2671]

santoshdada,
Grade A, B or C has nothing to do with the schedule of the pipe.
The various grades are classified based on Chemical Composition, Tensile/Yield Strength and Elongation.

The Piping Design Engineer will specify the Type and Grade of material based on service requirements. eg. ASTM A 106 Gr B.
The Engineer will then specify what schedule (thickness) of piping is required based on service conditions.eg. Sch 40, Sch 80, Sch 160 etc.
So your purchasing department may hypothetically purchase 100 lengths of ASTM A106 Grade B Sch 40, 100 lengths of A106 Gr B Sch 80, 100 lengths of A106 Gr B Sch 160.
Hope that helps,
Regards,
Kiwi

 

[santoshdada]

thx all