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Tube and pipe,what is the difference? (2)
Jul 20, 2017

Tube and pipe,what is the difference? (2)

To further clarify this understanding, Mr. E.A.Steen also enthusiastically sought out two official documents from the ASME Committee on the subject. As follows:

File NO.1

Interpretation:1-83-47

Subject:Section 1,PG-27, Definition of Pipe and Tube

Date issued:August 8,1979

File:BC79-501

Question: Do the rules of PG-27.2.2 define tubing and piping, respectively, by size only, or are there other criteria?

Reply: The formulas in Section 1, PG-27.2.1 ,for tubing are intended primarily for applications such as boiler tubes, or economizer tubes in which groups of such tubular elements are arranged within some enclosure for the purpose of transferring heat to or from the fluid within the tubes. For this heat transfer function, the tubular elements ordinarily do not need fittings or valves.

When the function to be performed is mainly the conveying of a pressurized fluid from one location to another, with litter or no intentional heat transfer, the tubular elements commonly used for this purpose are called piping. The standard piping sizes are available with the matching sizes of fittings (tees , elbows, etc.) and valves to facilitate the installation of piping systems to direct and control the flow. For such application, the formula for piping wall thickness in Section 1, PG-27.2.2 (or ANSI B31.1, Paragraph 104.1.2) , should be used.

File NO.2

Interpretation:1-86-25

 

Subject:Section 1, PG-27.2, wall Thickness of Pipe and Tube

 

Date:June 23, 1986

 

File:BC81-713, BC83-289, BC83-669, BC84-230

 

Question: Under what circumstances do the equations under PG-27.2.1 (for tubing) and PG-27.2.2 (for piping) apply?

 

Reply: The formulas in ASME Section 1, PG-27.2.1, for tubing, are intended primarily for applications such as boiler tubes, superheater and reheater tubes, or economizer tubes in which groups of such tubular elements are purpose of transferring heat to or from the fluid within the tubes. For this heat transfer function, the tubular elements ordinarily do not need fittings or valves.

 

When the function to be performed is mainly the conveying of a pressurized fluid from one location to another, with litter or no intentional heat transfer, the formulas in PG-27.2.2 should be used. The elements commonly used for this purpose are called piping. The standard piping sizes are available with matching sizes of fittings (tees, elbows, etc.) and valves to facilitate the installation of piping systems to direct and control the flow.

Thus, as early as 1979.8.8 and 1986.6.23, ASME issued a note number for the 1-83-47 and 1-86-25 files, answering users around the similar problems, to illustrate the definition for PG-27.2.1 tubing and PG-27.2.2 for piping.

Qestion 1: Are the tubing and piping determined only based on the diameter of the pipe or some other index?

Question 2: in what case, with the tubing formula PG-27.2.1, and in what case with the piping formula PG-27.2.2?

The answer to ASME is uniform:

ASME Article I ,PG-27.2.1 can be applied in the thickness formula of tube. It basically focuses on the furnace tube, superheater and reheater pipes, economizer tubes, pipes and so on . These pipe elements are arranged in a space arrangement and scope, aims to put the heat from the outside into or out of pressure medium inside the tube. A pipe to carry out such heat exchange is tubing, which generally does not need to be equipped with attachments (Tee, elbows) and valves .

If the action is only carried out to transporting compression medium from one location to another location, rather than focus on the medium in the pipe to convey process on the outside of the heat exchange, then use the PG-27.2.2 formula, the pipe in such use is called piping. In order to facilitate and control the flow of the conveying medium, the piping system is equipped with an accessory (Tee, elbow) and valve, and the standard size of the pipe matches the imported accessory device. The wall thickness formula is checked by PG-27.2.2 or ANSI B31.3, 104.1.2.

 

It seems that this is the original intention of ASME to differentiate between tube and pipe, and that it is also the proper source of all the tube and pipe distinguishing methods. All other understanding methods must refer to this fundamental explanation.

                                   Created and translated by Jack Hui

                                                            2017,7.19


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