SEAMLESS MECHANICAL TUBING COLD FINISH WALL THICKNESS TOLERANCE

 

 

FOR TUBING PRODUCED- OUTSIDE DIAMETER AND WALL

    Wall Thickness Tolerance Percent Over and Under Normal
Wall Thickness Flange As Percent of Outside Diameter
Outside Diameter 2.999” (76.19 mm) and smaller
Outside Diameter 3.000” (76.20 mm) to 5.999” (152.37 mm)
Outside Diameter 6.000” (152.40 mm) to 10.750” (273.05 mm)
Under 15
12.5
10.0
10.0
15 and over
10.0
7.5
10.0

 

Wall thickness tolerance may not be applicable to walls 9.199 inch (5.05 mm) and less’ consult manufacturer for wall tolerances on such tube sizes.

 

Produced Outside and Inside Diameter Tolerances for Round Cold-Worked Tuning a.b.c.

Thermal Treatment after Final Cold Work Producing Sizes

Outside Diameter Size Range,

In. d

Wall Thickness As Percent of Outside Diameter

None, or not exceeding 1 100 F Nominal Temperature OD,in.d ID,in.d

Heated above 1 100 F Nominal Temperature Without Accelerated Cooling OD, in.d ID,in.d.

Quenched and Tempered

 

 

ID,in.d ID,in.d

Over
Under
Over
Under
Over
Under
Over
Under
Over
Under
Over
Under
Up to 0.499
All
0.004
0.000
-
-
0.005
0.002
-
-
0.010
0.010
0.010
0.010
0.500-1.699
All

0.005

0.000
0.000
0.005
0.007
0.002
0.002
0.007
0.015
0.015
0.015
0.015
1.700-2.099
All
0.006
0.000
0.000
0.006
0.006
0.005
0.006
0.006
0.020
0.020
0.020
0.020
2.100-2.499
All
0.007
0.000
0.000
0.007
0.008
0.005
0.005
0.008
0.023
0.023
0.023
0.023
2.500-2.899
All
0.008
0.000
0.000
0.008
0.009
0.005
0.005
0.009
0.025
0.025
0.025
0.025
2.900-3.299
All
0.009
0.000
0.000
0.009
0.011
0.005
0.005
0.011
0.028
0.028
0.028
0.028
3.300-3.699
All
0.010
0.000
0.000
0.010
0.013
0.005
0.005
0.013
0.030
0.030
0.030
0.030

3.700-4.099

All
0.011
0.000
0.000
0.011
0.013
0.007
0.010
0.010
0.033
0.033
0.033
0.033
4.100-4.499
All
0.012
0.000
0.000
0.012
0.014
0.007
0.011
0.011
0.036
0.036
0.036
0.036
4.500-4.899
All
0.013
0.000
0.000
0.013
0.016
0.007
0.012
0.012
0.036
0.036
0.036
0.036
4.900-5.299
All
0.014
0.000
0.000
0.014
0.018
0.007
0.013
0.013
0.041
0.041
0.041
0.041
5.300-5.549
All
0.015
0.000
0.000
0.015
0.020
0.007
0.014
0.014
0.044
0.044
0.044
0.044
5.500-5.999
Under 6
0.010
0.010
0.010
0.010
0.018
0.018
0.018
0.018
 
6 to 7-1/2
0.009
0.009
0.009
0.009
0.016
0.016
0.016
0.016
 
Over 7-1/2
0.018
0.000
0.009
0.009
0.017
0.015
0.016
0.016
6.000-6.499
Under 6
0.013
0.013
0.013
0.013
0.023
0.023
0.023
0.023
 
6 to 7-1/2
0.010
0.010
0.010
0.010
0.018
0.018
0.018
0.018
 
Over 7-1/2
0.020
0.000
0.010
0.010
0.020
0.015
0.018
0.018
6.500-6.999
Under 6
0.015
0.015
0.015
0.015
0.027
0.027
0.027
0.027
 
6 to 7-1/2
0.012
0.012
0.012
0.012
0.021
0.021
0.021
0.021
 
Over 7-1/2
0.023
0.000
0.012
0.012
0.026
0.015
0.021
0.021
7.000-7.499
Under 6
0.018
0.018
0.018
0.018
0.032
0.032
0.032
0.032
 
6 to 7-1/2
0.013
0.013
0.013
0.013
0.023
0.023
0.023
0.023
 
Over 7-1/2
0.026
0.000
0.013
0.013
0.031
0.015
0.023
0.023
7.500-7.999
Under 6
0.020
0.020
0.020
0.020
0.035
0.035
0.035
0.035
 
6 to 7-1/2
0.015
0.015
0.015
0.015
0.026
0.026
0.026
0.026
 
Over 7-1/2
0.029
0.000
0.015
0.015
0.036
0.015
0.026
0.026
8.000-8.499
Under 6
0.023
0.023
0.023
0.023
0.041
0.041
0.041
0.041
 
6 to 7-1/2
0.016
0.016
0.016
0.016
0.028
0.028
0.028
0.028
 
Over 7-1/2
0.031
0.000
0.015
0.016
0.033
0.022
0.028
0.028

a.. Many tubes with inside diameter less than 50% of outside diameter or with wall thickness more than 25% of outside diameter, or with wall thickness over 1-1/4 in., or weighing more than 90 lb/ft are difficult to draw over mandrel. Therefore, the inside diameter can vary over or under by an amount equal to 10% of the wall thickness. See also Footnote b.

 

b. For those tubes with inside diameter than % in. (or less than _ in., when the wall thickness is more than 20% of the outside diameter), which are not commonly drawn over a mandrel. Footnote is applicable. Therefore, for those tubes, the inside diameter is governed by the outside diameter shown in this table and the wall thickness tolerances shown in Table 7b.

 

c. Tubing having a wall thickness than 3% of the4 outside diameter cannot be straightened properly without certain amount of distortion. Consequently such tubes, while having an average outside diameter and inside diameter within tolerances shown in the table, require an ovality tolerance of 1/2% over and under nominal diameter, this being in addition to the tolerance indicated in this table. d 1 in = 25.4 mm

 

Additional Quality
OD, Inches
Tolerances, Inches
Up to 2,000
Incl.
.010
Over
2.000 - 3.000
Incl.
.015
Over
3.000 - 4.000
Incl.
.020
Over
4.000 - 5.000
Incl.
.025
Over
5.000 - 6.000
Incl.
.030
Over
6.000 - 7.000
Incl.
.035
Over
7.000 - 8.000
Incl.
.040
Over
8.000 - 9.000
Incl.
.045
Over
9.000 - 10.000
Incl.
.050
Over
10.000 - 11.000
Incl.
.055
Over
11.000 - 12.000
Incl.
.060
Over
12.000 - 12.5000
Incl.
.065

 

 

For Material Produced O.D. and Wall Thickness Tolerances for Round Cold-Worked Tubing

Wall Thickness Range as % Of Outside Diameter Wall Thickness Tolerance, Over and Under Nominal, % 1.500 in and over
25 and under
10.0%
7.5%
Over 25
10.0%
10.0%

 

 

ROUND COLD-FINISHED TUBING OUTSIDE AND WALL THICKNESS TOLERANCES

    Wall Thickness Tolerance, Percent Over and Under Normal
Wall Thickness Flange As Percent of Outside Diameter
Outside Diameter 1.500 (38.09 mm) to 3.000 (76.20 mm)
Outside Diameter 3.000” (76.20 mm) to 5.999” (152.37 mm)
Outside Diameter 6.000” (152.40 mm) to 10.750” (273.05 mm)
Under 15
1.5
10.0
10.0
15 and Over
10.0
7.5
10.0

Wall thickness tolerance may not be applicable to walls 9.199 inch (5.05 mm) and less’ consult manufacturer for wall tolerances on such tube sizes.

 

MAXIMUM DEPTH LIMIT IF SURFACE IMPERFECTIONS OF O.D. AND I.D. – TUBING

 

The following table shows the permissible depth of surface Imperfections. Determination should be made by measuring the actual diameter or wall thickness at the place of imperfection, filling it out, and remeasuring.

SPECIFIED O.D.
COLD DRAWN
1.4999
.010
1.500/1.999
.013
2.000/2.499
.015
2.500/2.999
.018
3.000/3.499
.020
3.500/3.999
.023
4.000/4.499
.025
4.500/4.999
.028
5.000/5.499
.030
5.500/5.999
.035
6.000/6.499
.038
6.500/6.999
.040
7.000/7.499
.043
7.500/7.999
.045
8.000/8.499
.050
8.500/8.499
.055
9.000/9.499
.060
9.500/9.999
.065
10.000/10.499
.070
10.500/10.750
.075
10.750/11.000
----------

 

 

Size Limits
Maximum Curvature in any 3 ft. In. (mm)
Maximum Curvature in Total Lengths, In. (mm)
Maximum Curvature In Total Lengths 3 ft or 1 m
OD 5 in. (127.0 mm) and smaller. Wall thickness over 3% of OD but not over 0.5 in. (12.7 mm)
0.030 (0.083)
0.030 x (no. of ft of length/3) (0.083 x no. of m of length)
Ratio of 0.010 in./ft or 0.83 mm/m
OD 5 in. to 8 in. (127.0 to 203.2 mm), incl. Wall thickness over 4% of OD but not over 0.75 in. (19.0 mm)
0.045 (1.25)
0.045 x (no. of ft of length/3) (1.25 x no. of m of length)
Ratio of 0.015 in./ft or 125 mm/m
OD 8 in. to 12-3/4 in. (203.2 mm to 323.8 mm), incl. Wall thickness over 4% of OD but not over 1.0 in. (25.4 mm)
0.060 (1.67)
0.060 x (no. of ft of length/3) (1.67 x no. of m of length)
Ratio of 0.020 in./ft or 16.7 mm/m

 

Length Tolerances for Round Cold Finished Tubing

 

NOTE- The producer should be consulted for the length tolerances for tubes produced by liquid –or air quenched heat treatment.

Length, ft. (in.)
Outside Diameter, in. (mm)
Tolerance , In. (mm) Over
Tolerance, in. (mm) Under
4 (1.2) and under
Up to 2 (50.8), incl.
1/16 (1.6)
0
4 (1.2) and under
Over 2 to 4 (50.8 to 101.6), incl.
3/32 (2.4)
0
4 (1.2) and under
Over 4 (101.6)
1/8 (3/2)
0
Over 4 to 10 (1.2 to 3.0), incl.
Up to 2 (50.8), incl.
3/32 (2.4)
0
Over 4 to 10 (1.2 to 3.0), incl.
Over 2 (50.8)
1/8 (3/2)
0
Over 10 to 24 (3.0 to 7.3), incl.
All sizes
3/16 (4.8)
0

 

 

SEAMLESS MECHANICAL TUBING

TUBING SPECIFIED TO O.D. AND I.D. DIMENSIONS IS RECOMMENDED FOR MACHINING AND OTHER

APPLICATIONS REQUIRING AN ACCURATE INSIDE DIAMETER

 

EXAMPLE: Tubing specified to O.D. and I.D. dimensions 4, ½” O.D. x 4 “ I.D. O.D. 4.500/4.513” I.D. 3.987/4.00” Wall +/- 7.5% of .250/.263” or .231/.283”

 

Tubing specified to O.D. and Wall dimensions 4-½” O.D. x 1/4 “wall. O.D. 4.500/4.513” I.D. 3.962/4.051” Wall +/- 7.5% of .250 or .231/.269”

 

MACHINING ALLOWANCES FOR TUBING FROM WAREHOUSE STOCK

 

The following procedure may be used to determine the proper warehouse stock size (O.D. and wall thickness) of Cold Drawn Seamless or Buttweld Steel Tubing with sufficient allowance for machining based in chucking true to O.D.

 

A= Machined O.D. (Maximum)

B= Machining allowance, O.D. or I.D.

Under 1-1/2” O.D. .020”

1-1/2” to 3” Excl. 0.40”

3” to 5-1/4” Excl. 0.60”

5-1/2” to 8” Excl. 0.80”

 

C= Camber in length of part, ratio per foot

Under 5” O.D. .020”

5” to 8” Excl. .030”

8” to 10-3/4” .040”

Calculated O.D. = A + B + C

D= Machined I.D. (Minimum)

E = Outside Diameter Tolerance

F = Percent of Wall Thickness Tolerance

 

Stock Size O.D. –When the calculated O.D. is not shown as available in the stock list use the stock size O.D. listed which is next larger than the calculated O.D.

 

Calculated I.D. = D – (B + C)

Calculated Wall Thickness (Stock Size O.D. + E – Calculated I.D.) (1.00 + F)

 

Stock Size Wall Thickness – When calculated wall thickness is not shown as available in the stock size O.D. above, use the ctock size wall thickness

listed which is next heavier.

 

MACHINING ALLOWANCES FOR ALLOY MECHANICAL TUBING

OD
Commercial Quality FOR C.D. (Per Size)
Magnaflux Quality FOR C.D. (Per Size)
½” to 1-1/2”
.010”
.035”
1-1/2”
.020”
.045”
Over 3” to 4”
.030”
.055”
Over 4-1/2” to 5-1/2”
.030”
.055”
Over 5-/2” to 6-1/2”
.040”
.065”
Over 6-1/2” to 8”
.040”
.065”
Over 8” to 10”
.050”
.075”

Note”

(a) Same on I.D as O.D

(b) For magnaflux quality .025” per side was added for C.D.

(c) Over 10” consult Carbon & Alloy Steel Corp.

(d) Above allowances do not include heat treated material

 

Notes: If the machine part is less than 4” long or the maximum machined O.D. and minimum machined I.D. is within 4” of the chuck, camber may be ignored. Also, the formula assumes that tolerances, surface defects, eccentricity, and camber are all at the permissible maximum at the same time. Since this condition is extremely unlikely a stock size slightly under either the calculated O.D. or wall may sometimes be used to advantage with the risk offset by the savings in material cost.

 

Straightness Tolerances for Seamless Round Mechanical Tubing

Note 1- The straightness variation for any 3 ft (0.90 m) of length is measured with a 3 ft. straightedge and the use of a feeler gage. The total variation, that is the maximum Curvature at any point in the total length of the tube, is determined by rolling the tube ib a surface plate and measuring the concavity with a feeler gage.

Note 2 – the tolerances apply generally to annealed, finished-annealed and medium annealed cold-finished or hot finished tubes. When straightening stresses would interfere with the use of the end product the straightness tolerances shown do not apply when tubing is specified “not to be straightened after furnace treatment”. These straightness tolerances do not apply to soft annealed or quenched and tempered tubes.

 

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