Message from
Chairman of Central Boilers Board


About Central Boilers
Board


History of Indian Boiler Regulations

Foreword

Contents Chapter
Wise


Contents Regulation
Wise


List of Amendments

Indian Boilers
Act 1923


Ibr Forms

Home

Search

Help

Contact Us

 

Reg. 554

Manhole frames, mouthpieces and doors

 

Manhole frames, mouthpieces, doors or cover plates shall be of mild steel. Frames shall be oval and where of the flanged type shall be formed to bed closely to the shell and provided a flat jointing surface to the door. Alternatively, raised circular mouthpieces may be fitted externally and where of the flanged type shall be bedded closely to the shell.

Wherever practicable the frame shall be attached to the inside of the shell with the shorter axis parallel to the longitudinal centre line of the boiler. In all cases where the shell thickness exceeds 9/16 inch, oval frames or circular mouthpieces shall be fitted.

Doors shall be made from mild steel plate formed to bed closely to the internal surface and shall be fitted with studs, each provided with an integral collar and screwed through the plate with a nut on the inside of the door or fillet welded on the inside, the length of the leg of the fillet weld being not less than one quarter of the diameter of the stud or riveted on the inside of the door. Doors for openings larger than 9 inches x 7 inches shall have two studs, but for doors of size 9 inches x 7 inches or less only one stud need be fitted; doors for openings not larger than 5 inches x 3 ½ inches may have the stud forge solid with the door. Where the door of a mudhole, cleaning hole or sight hole is fabricated by welding for boilers not exceeding a working pressure of 8.8. kg./cm. (125 lbs. per sq. inch). The stud shall pass through the plate and be secured to it by strength-welding on the inside and fillet-welding on the outside to the satisfaction of the Inspecting Authority. The door shall be stress relieved by heat treatment after welding.

The cross bars shall be of substantial proportions and either solid steel forging or cast steel. Lugs may be satisfactorily welded to manhole doors for the attachment of the bolts.

The spigots of the door when it is in a central position in the manhole have a clearance of not more than 1/16 inch all round.

Oval frames and externally raised circular mouthpieces shall be either:-

a) Formed in one piece without weld, or
b) Formed from a suitable rolled section and forge-welded, or fabricated by fusion welding, provided they are stress-relieved by heat-treatment after welding and before attaching to the boiler unless the whole boiler is to be subjected to heat-treatment on completion.

Welds shall be positioned so that they are located on the transverse centre line of the boiler(see Regulation 556).

The joining flanges of mouthpieces and covers shall be machined on the face and edges and on the bearing surface for the bolts. Bolts and nuts shall be machined where in contact with the flanges and the joints should be formed inside and outside the pitch line or pitch circle of the bolts to preclude the possibility of flange distortion. Cover plates shall be dished outwards to a depth of approximately one-eighth of the internal diameter of the frame.

All edges shall be machined or flame-cut by machine (see Regulation 541).

Forms or manhole frames and attachments are shown in Figures XII/52, XII/53, XII/54, XII/55 and XII/56.

 
Back   Top
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
Indian Boilers Act 1923 Ibr Forms Home Search Help Contact Us