Section 170.270 - Door design, operation, installation, and testing(a) Each Class 1 door must have a quick action closing device operative from both sides of the door.(b) Each Class 1 door on a vessel in ocean service must be designed to withstand a head of water equivalent to the depth from the sill of the door to the margin line but in no case less than 10 feet (3.05 meters).(c) Each Class 2 and Class 3 door must- (1) Be designed, constructed, tested, and marked in accordance with ASTM F 1196 (incorporated by reference, see § 170.015 );(2) Have controls in accordance with ASTM F 1197 (incorporated by reference, see § 170.015 ); and(3) If installed in a subdivision bulkhead, meet Supplemental Requirements Nos. S1 and S3 of ASTM F 1196 (incorporated by reference, see § 170.015 ), unless the watertight doors are built in accordance with plans previously approved by the Coast Guard, in which case, only Supplemental Requirements Nos. S1 and S3.1.4 of ASTM F 1196 (incorporated by reference, see § 170.015 ) must be met. In either case, control systems for watertight doors must have power supplies, power sources, installation tests and inspection, and additional remote operating consoles in accordance with Supplemental Requirements Nos. S1 through S4 of ASTM F 1197 (incorporated by reference, see § 170.015 ).(d) Installations of sliding watertight door assemblies must be in accordance with the following: (1) Before a sliding watertight door assembly is installed in a vessel, the bulkhead in the vicinity of the door opening must be stiffened. Such bulkhead stiffeners, or deck reinforcement where flush deck door openings are desired, must not be less than 6 inches nor more than 12 inches from the door frame so that an unstiffened diaphragm of bulkhead plating 6 to 12 inches wide is provided completely around the door frame. Where such limits cannot be maintained, alternative installations will be considered by the Marine Safety Center. In determining the scantlings of these bulkhead stiffeners, the door frame should not be considered as contributing to the strength of the bulkhead. Provision must also be made to adequately support the thrust bearings and other equipment that may be mounted on the bulkhead or deck.(2) Sliding watertight door frames must be either bolted or welded watertight to the bulkhead. (i) If bolted, a suitable thin heat and fire resistant gasket or suitable compound must be used between the bulkhead and the frame for watertightness. The bulkhead plating must be worked to a plane surface in way of the frame when mounting.(ii) If welded, caution must be exercised in the welding process so that the door frame is not distorted.(e) For each watertight door which is in a required subdivision bulkhead, an indicator light must be installed in the pilothouse and at each other vessel operating station from which the door is not visible. The indicator must show whether the door is open or closed.CGD 79-023, 48 FR 51010, Nov. 4, 1983, as amended by CGD 88-032, 56 FR 35828, July 29, 1991; CGD 85-080, 61 FR 944, Jan. 10, 1996; USCG-2000-7790, 65 FR 58464 , Sept. 29, 2000