Pipe grade & pipe Schedule

[WAT]

good morning all
I'm new in piping , I need to know what is the different between Pipe grade and pipe Schedule and haw I can choose the right grade and right Schedule
is there any recomended books

thanks for every thing

[cybersoul]

refer to earlier posts, there are some good piping books.and also download Practical guide to ASME B31.3 process piping.
"Schedule is expressed in numbers (5, 5S, 10, 10S, 20, 20S, 30, 40, 40S, 60, 80, 80S,
100, 120, 140, 160). A schedule number indicates the approximate value of the
expression 1000 P/S, where P is the service pressure and S is the allowable stress,
both expressed in pounds per square inch (psi). The higher the schedule number,
the thicker the pipe is. The outside diameter of each pipe size is standardized.
Therefore, a particular nominal pipe size will have a different inside diameter
depending upon the schedule number specified. "
Taken from Piping handbook 7th Edition.
Choosing the right schedule and grade depends upon design conditions like temp,pressure, allowable stress etc.

[john1964]

Compiled some pipe data & have gathered from several sources to simplify the concept.

What is nominal pipe size??
"Nominal" means "in name only". Thus it could be the inside diameter or the outside diameter.
For steel pipes: The ANSI sizes are based on the old IPS (Iron Pipe Size) standard.
• The Nominal Diameter is roughly the ID (inner diameter) for sizes up to 12”. For sizes 14" and above the Nominal Diameter is the OD (outer diameter). In other words, up-to 12" NPS is ID; For 14" NPS and larger it’s the OD.
Example- 12" nominal pipe is 12.75 OD; 14" nominal pipe is 14" OD; 18" nominal pipe is 18" OD.
• In case we use sizing pipes for flow of fluids then the ID is always used.
• In case we enquire about actual pipe sizes then these are based on the Nominal Size (e.g. 2",3",4",6",8",10”,12” etc). The OD of an actual pipe is dependent on the nominal pipe size & is constant.
• The actual ID of a pipe is dependent upon the pipe schedule & varies with the schedule.
• For example -
Nom Pipe Size // Pipe O.D. // Pipe I.D.
3" // 3.5" // Depends on pipe Schedule
4" // 4.5" // Depends on pipe Schedule
6" // 6.625" // Depends on pipe Schedule
8" // 8.625" // Depends on pipe Schedule
10" // 10.75" // Depends on pipe Schedule
12" // 12.75" // Depends on pipe Schedule

14" and Above - the Pipe OD is the nominal size of the pipe and the ID depends on the pipe schedule.

How to remember the OD’s of nominal pipe size below 12”??
3” and 4” have OD’s 0.500” larger than the nominal ID
6" and 8" have ODs 0.625” larger than the nominal ID.
10" and 12" have ODs 0.750” larger than the nominal ID. That is, 12" pipe has an OD of 12.750.

What is pipe schedule??
Pipe schedule defines wall thickness. The schedule numbers does not change the OD which remains as a constant; but on the other hand it changes the ID.
Example a schedule 40 pipe will be thin walled compared to schedule 160 which will be extra thick.
Explore the following useful link:

[link Point to another website Only the registered members can access]
For material specifications refer codes- ASME B-31.3 process piping guide. Refer the link-

[link Point to another website Only the registered members can access]
Elaborate pipe schedule.
The pipe schedule refers to the pipe wall thickness. The higher the schedule, the thicker is the pipe wall. For example:

2-inch nominal size steel pipe: schedule 40 has a wall thickness of 0.154 inches and schedule 80 has a wall thickness of 0.218 inches.

4-inch nominal size steel pipe: schedule 40 has a wall thickness of 0.237 inches and schedule 80 has a wall thickness of 0.318 inches.

As you can see, the relationship between schedule and wall thickness changes with the pipe nominal size.

Best regards, John 1964
Safety is as simple as ABC.......Always Be Careful.

[anil4u29]

thank you

[anish]

Sir,
am presently doing MTech in pipeline industry.....
for my semi project the topic i get is city gas pipelin please helpme....
give me some idea regarding it
my email id anishsrkvk@gmail.com

[Quibo]

Thanks a lot John

[mrk]

thanks john.........

[vipin.kesharwani21]

please farward me useful data for piping design n
stress analysis

[gracey]

Hello, anyone please help me, what is the difference between the grade A and grade B for pipe. I've been trying to source for suppliers for grade A pipe, but usually the suppliers will give me grade B.

[jandonian]

Dear Gracey

In my part of the world we face the same problem where the pipe suppliers do not sell Grade A pipe. By the way Grade B is better than Grade A. Tensile strength of Grade A is 48Ksi when the tensile strength of Grade B material is 60ksi (ASTM A53, API5L).

When you look at the composition of both the material (ASTM A53) there is a marginal difference (only carbon and manganese contents are different) so I guess the cost of production by the steel mills for both material grade is almost the same but the yield strength of grade B is about 25% higher.

Material Composition
Carbon Manganese Phosphorus Sulfur Copper Nickel Chromium Molybdenum Vanadium
Grade A 0.25 0.95 0.05 0.045 0.40 0.40 0.40 0.15 0.08
Grade B 0.30 1.20 0.05 0.045 0.40 0.40 0.40 0.15 0.08

When selecting the proper thickness of the pipe this give you cost benefit as the t=pD/2S, where S is percentage of min yield strength. Higher the S value lower shall be the thickness and as a rule the steel pipe prices are function of weight (lesser the thickness lesser shall be the weight).

For further analysis you can see graph 1-7 Typical Pipeline Grade Cost in book "Pipeline Design and Construction: A practical Approach". In simple words it can be stated that we can achieve a cost saving due to reduced thickness by employing higher grade materials for the same design pressure.

I hope i am able to make sense!

[gracey]

Dear Jandonian,

Yes, you really make sense. Thank you.

[alexcv]

thanks