[Code of Federal Regulations]
[Title 46, Volume 2]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR52.01-105]

[Page 129]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 52_POWER BOILERS--Table of Contents
 
                   Subpart 52.01_General Requirements
 
Sec. 52.01-105  Piping, valves and fittings (modifies PG-58 and PG-59).

    (a) Boiler external piping within the jurisdiction of the ASME Code 
must be as indicated in PG-58 and PG-59 of the ASME Code except as noted 
otherwise in this section. Piping outside the jurisdiction of the ASME 
Code must meet the appropriate requirements of part 56 of this 
subchapter.
    (b) In addition to the requirements in PG-58 and PG-59 of the ASME 
Code, boiler external piping must:
    (1) Meet the design conditions and criteria in Sec. 56.07-10 of 
this subchapter, except Sec. 56.07-10(b);
    (2) Be included in the pipe stress calculations required by Sec. 
56.31-1 of this subchapter;
    (3) Meet the nondestructive examination requirements in Sec. 56.95-
10 of this subchapter;
    (4) Have butt welding flanges and fittings when full radiography is 
required; and
    (5) Meet the requirements for threaded joints in Sec. 56.30-20 of 
this subchapter.
    (c) Steam stop valves, in sizes exceeding 152mm (6 inch) NPS, must 
be fitted with bypasses for heating the line and equalizing the pressure 
before the valve is opened.
    (d) Feed connections. (1) Feed water shall not be discharged into a 
boiler against surfaces exposed to hot gases or radiant heat of the 
fire.
    (2) Feed water nozzles of boilers designed for pressures of 2758 kPa 
(400 psi), or over, shall be fitted with sleeves or other suitable means 
employed to reduce the effects of metal temperature differentials.
    (e) Blowoff connections. (1) Firetube and drum type boilers shall be 
fitted with a surface and a bottom blowoff valve or cock attached 
directly to the boiler or to a short distance piece. The surface blowoff 
valve shall be located within the permissible range of the water level, 
or fitted with a scum pan or pipe at this level. The bottom blowoff 
valve shall be attached to the lowest part of the boiler or fitted with 
an internal pipe leading to the lowest point inside the boiler. 
Watertube boilers designed for pressures of 2413 kPa (350 psig) or over 
are not required to be fitted with a surface blowoff valve. Boilers 
equipped with a continuous blowdown valve on the steam drum are not 
required to be fitted with an additional surface blowoff connection.
    (2) Where blowoff pipes are exposed to radiant heat of the fire, 
they must be protected by fire brick or other suitable heat-resisting 
material.
    (f) Dry pipes. Internal dry pipes may be fitted to the steam drum 
outlet provided the dry pipes have a diameter equal to the steam drum 
outlet and a wall thickness at least equal to standard commercial pipe 
of the same diameter. Openings in dry pipes must be as near as 
practicable to the drum outlet and must be slotted or drilled. The width 
of the slots must not be less than 6mm (0.25 in.). The diameter of the 
holes must not be less than 10mm (0.375 in.). Where dry pipes are used, 
they must be provided with drains at each end to prevent an accumulation 
of water.

[CGD 81-79, 50 FR 9432, Mar. 8, 1985]