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Reg. 53 c
MATERIALS OF CONSTRUCTION

SEAMLESS FERRITIC PIPES FOR HIGH TEMPERATURE SERVICE

Workmanship and tolerance

The pipes shall be well finished, cleaned free from harmful defects.  They shall be reasonably straight, smooth, cylindrical and subject to the following tolerances.  Pipes manufacturer shall explore a sufficient number of visual inspections to provide reasonable assurance that they have been properly evaluated. 

(i) Permissible variation in outside diameter. 

For all grades except X20CrMoV121

Hot finished and Cold finished seamless pipes

Outside diameter (mm)     

                     

Permissible variations (mm)

Over

Under

10.3 to 48.3 incl.

0.40

0.40

Over 48.3 to 114.3 incl.

0.79

0.79

Over 114.3 to 219.1 incl.

1.58

0.79

Over 219.1 to 300 incl.

2.38

0.79

Over 300.

1%

1%

       

                  For Grade X20CrMoV121

Outside diameter (mm)

Permissible variations (mm)

Over

Under

 

100 and under

0.75%

0.75%

 

Over 100 to 320 incl.

0.90%

0.90%

Over 320

1.00%

1.00%

         

(ii)  Permissible variations in wall thickness :

For all grades, except X20CrMoV121

The minimum wall thickness at any point shall not be more than 12.5% under the nominal wall thickness specified

For grade X20CrMoV121

Outside diameter (mm)

Permissible variation %

Over

Under

100 and under

12.5

10

Over 100 to 320 incl.

12.5

12.5

Over 320

15.0

12.5

(iii)  Permissible  variation in length :

Seamless Hot finished and Cold finished pipes can be ordered in specified length or in random length.  If ordered in specified length, the tolerance shall be as follows :

                  For hot finished and cold finished pipes

Grade

Length (m)

Permissible variation in (mm)

Over                        Under

All  grades except

X20CrMoV121

All length

    6                               0

For grade

X20CrMoV121

6 and under

Over 6 to 12 incl.

10                             0

   15                               0


 
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Message from Chairman of Central Boilers Board About Central Boiler Board History of Indian Boiler Regulations Foreword Contents Chapter Wise Contents Regulation Wise List of Amendments
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