One of the things that engineers in all industries will have to deal with it somehow, and one of the fundamental issues is complete understanding of the difference between pipes and tubes, be. Attempt has been made to this topic differences between pipes and tubes are examined in detail and examples. The article by Mr. Ebrahim No, Inspection Engineer Iranian Offshore Oil Company (Bahregan area) has been prepared.
What is a pipe?
Container with a circular hollow tube (diameter, thickness and length specified) for the handling and transmission fluids are used. And can be made of different materials. Steel, concrete, fiberglass and ... .
The pipes are made from welded pipes and seamless tubes two friend are classified. Sample tubes are common:
ASTM A53
Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless
ASTM A106
Specification for Seamless Carbon Steel Pipe for High-Temperature Service
ASTM A333
Specification for Seamless and Welded Steel Pipe for Low-Temperature Service
1 - seamless pipe Seamless Pipe
It uses tubes and solid bars with circular cross sections and the rollers are produced by heating and stretching. Usually up to 16 inches in diameter seamless pipes are made.
2 - Pipe Welded Pipe seamy
To make it out of steel and welded pipes used. Submerged arc welding steel pipes are usually two ways (SAW) and electric resistance welding (ERW) are produced. The welded pipe joints are divided into two types:
?? Straight seam pipe Straight Seam Pipe
?? Spiral welded pipes Spiral Seam Pipe
Dimensions of pipes
NPS Nominal Pipe Size Nominal diameter pipe
Inside diameter of the pipe ID Internal Diameter
OD Outside Diameter Outside Diameter Tubing
SCHEDULE or pipe thickness class (SCH)
Thickness t or wall Thickness
Length L or Length
Make a Pipe End Preparation
Concepts of ID, OD, NPS for pipe
First Law: OD pipes have to be fixed though the thickness varies. A fixed nominal pipe diameter for different diameter, outer diameter is the same. For example, the outer diameter (OD) pipe with an 8 inch Sch 40, Sch 60, .... And is equal to 8.625 inch.
Act II: up to size 12> = NPS, nominal diameter (NPS) and outer diameter (OD) pipes are not the same outer diameter greater than the nominal diameter (OD> NPS) is. For example, a pipe with a nominal diameter of 10 inches, OD is equal to 10.750 inches.
Act III: The size of 14 inches and dimensions (NPS ≥ 14) outer diameter OD pipe with the same nominal diameter is NPS.
Compressive strength classification of pipe
A-weighting method: This method is the oldest method. Specified for each pipe diameter, the weight specified by the standard (STD) have a contract. This method is approved by ASME and ASTM. Will be discussed in more detail in this area.
(B) Application method: In this method, the pressure pipe into 1,000 times the allowable stress is used. Together with the number and name are known Schedule Number., This method is approved by ANSI.
C: Coding Method: In this method, first proposed standard based on the maximum stress at yield and grade of pipe is introduced. Accordingly pipes with grades of A, B, X42, X46, X52, X56, X60, X65, X70 , U89, U100 are identified. example, a tube profile API - 5LS - X60 spiral pipe is made in the yield strength is 60000PSI.
Classifieds thick pipe (Schedule No)
Pipe thickness class of pipe to be used in order to facilitate trade. For example, instead of saying 9.27mm thickness of the tube is 10 inches, 10 inch Sch 40 pipe
Thumb formula for calculating Sch No:
A = (3 + ID) / WT
A number of assumptions
Inner diameter ID
WT thickness
However Classifieds thickness (Sch) based on the number of A and obtains the following table.
Sch No
A Number Range
Sch 30
40 ~ 50
Sch 40
29 ~ 39
Sch 60
25 ~ 29
Sch 80
20 ~ 23
Sch 100
16 ~ 18
Sch 120
13 ~ 15
Sch 140
11 ~ 13
Sch 160
9 ~ 11
Key points about Sch No
First rule: for a constant diameter pipe, Sch No matter what rises is too thick. Example:
8 inch Sch 30 t = 7.04 mm
8 inch Sch 40 t = 8.18 mm
8 inch Sch 60 t = 10. 53,
Act II: In order to facilitate the use of common business classes thickness names are as follows:
Standard: STD
Extra Standard: XS
Double Extra standard: XXS Sch> 160
Note: The thickness of pipes such as high Sch 120,140,160, XXS pipe is also called the Heavy Wall.
Act III:
10 ≥ NPS-inch class sizes and thickness STD Sch 40 are identical.
For all pipe sizes above 10 inches thick with STD Classifieds thickness 9.53mm (3/8 inch) will be. Example:
6 inch Sch 40 = STD, t = 7.11
10 inch Sch40 = STD, t = 9.27
12 inch Sch STD, t = 9.53
Act IV:
Classes inches thick and 8 ≥ NPS sizes XS Sch 80 are identical.
For all pipe sizes above 8 inches thick Classifieds XS has a thickness of 12.7mm (1/2 inch) will be. Example:
6 inch Sch 80 = Sch XS, t = 10.97
10 inch Sch 60 = Sch XS, t = 12.7
12 inch Sch 80 = Sch XS, t = 12.7
First point: Only 10-inch class sizes XS thicknesses are Sch 60 times.
Point two classes only up to size 12 inch thick XXS there.
What is YouTube?
Usually tubes for high pressure and high temperature heat transfer applications are used and are resistant to creep. The tubes in boilers, oil furnaces, heat exchangers are used.
Seamless tubes and usually built up size is 12 inches.
Tubes with specified length of pipe joinery, while the length is specified.
Tubes is the same thickness throughout the length of the tube while the tube wall along their length is a dimensional tolerance.
Sample tubes are common in the industry:
ASTM A178
Specification for Electric-Resistance-Welded Carbon Steel and Carbon-Manganese Steel Boiler and Superheater Tubes
ASTM A179
Specification for Seamless Cold-Drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes
ASTM A192
Specification for Seamless Carbon Steel Boiler Tubes for High-Pressure Service
ASTM A209
Specification for Seamless Carbon-Molybdenum Alloy-Steel Boiler and Superheater Tubes
ASTM A210
Specification for Seamless Medium-Carbon Steel Boiler and Superheater Tubes
Profile of tubes
Nominal diameter tubes with outer diameter is the same.
Example: Tube OD ¾ or ¾ inch diameter tube has an outer diameter of 6 inches 6 inches.
Tube thickness Classifieds BWG (Birmangham Wire Gauge) is specified.
Tubes of 00 gauge double zero (maximum diameter, 9mm) and 36 starts (minimum thickness 0.1mm) ends.
Increased BWG (gauge tube) tube thickness is reduced. (Sch In contrast piping)
Example:
6 inch tube BWG 12, t = 2.76mm
6incn tube BWG 16, t = 1.65mm
5. BWG is independent of tube diameter. In other words, a few tubes of different diameters but the same BWG are the same thickness. Example
6 inch tube, BWG 22, t = 0.711 mm
8 inch tube BWG 22, t = 0.711 mm
½ inch tube, BWG 22, t = 0.711 mm
6. OD tube as the tube is permanently fixed. A fixed tube diameter (eg 2 inches) and different gauge fixed diameter (2 inches) or more. In other words, with the increased thickness of the tube (lower gauge) ID tube diameter decreases, but it is constant. Example:
1 inch tube BWG 20, t = 0.89 mm, OD = 1 inch, ID = 0.930 inch
1 inch tube BWG 12, t = 2.76 mm, OD = 1 inch, ID = 0.782 inch
No comments:
Post a Comment