For purposes of this section, the replacement of existing steam piping systems, the installation of a new system in existing buildings, as well as installations in buildings hereafter constructed, shall be considered to be new high-pressure steam piping systems. The following requirements are applicable:
The design of new steam piping systems shall be conducted as follows:
- The system shall be designed by an engineer. An application and plans shall be filed and the approval of the department obtained. The plans and application shall contain, but not be limited to, the following information:
- Size and location of all steam piping.
- The operating pressures and temperatures.
- The location, type, specifications and details of all expansion joints.
- The design, size, material and location of all anchors, guides and auxiliary steel, and the stresses thereon.
- Systems using utility street steam shall be designed for a pressure of 200 psig (1379 kPa) and 413°F (212°C) up to and including the steam pressure reducing valve or valves which reduce the pressure of 90 psig (621 kPa) or below. For steam pressures between 90 psig (621 kPa) and 16 psig (110 kPa), the system shall be designed for 125 psig (108 kPa).
- Steam distribution systems utilizing pressure reducing valves.
- Safety Shutoff Valves ("SSO") to protect downstream piping from overpressure shall be allowed in lieu of a safety relief valve vented to the outdoors as required by Section 1006.6
- SSO shall be designed to automatically close at or below the design pressure of the downstream piping system that is being protected, to provide positive shutoff against full upstream pressure. Manual reset shall be required to reopen the SSO.
- SSO shall be designed in accordance with the Steam Distribution Utility System requirements of the utility company having jurisdiction and ASME B31.1.
- Bellows expansion joints shall not be utilized on high pressure steam piping.
The installation of new steam piping systems shall be conducted as follows:
- Installations, including any welding, shall be subject to special inspection.
- Welders shall be qualified for all required pipe sizes, wall thicknesses and positions in accordance with the ASME Boiler and Pressure Vessel Code, Section IX. Requalification is required every five years or sooner if the commissioner has a specific reason to doubt a welder's ability to make acceptable welds.
- Welder qualification testing shall be performed by an approved agency listed with the department, and the inspector witnessing the test shall be an authorized AWS Certified Welding Inspector. If the testing is by radiography, the test specimen shall be evaluated by personnel having a minimum radiography qualification of Level II in accordance with the ASNT, Document No. SNT-TC-1A, Supplement A. A successful radiographic test of a production weld made within the 6 months prior to requalification may be considered as an acceptable requalification test.
- Copies of the certified welder qualification reports shall be maintained by the responsible welding agency and the company performing the welding, and shall be made available upon request to the department.
- No reports from any welding inspection agency shall be accepted unless such agency has first requested and obtained approval from the department in accordance with rules of the department.
- Pipe welding shall conform to the following:
- All piping over 2 inches (51 mm) shall be butt-welded. Piping 2 inches (51 mm) and under may be socket-welded or threaded, providing Schedule 80 piping is utilized.
- Threaded piping may continue to be used for existing construction in sizes of 6 inches (152 mm) and under.
- Where welding is not feasible, the commissioner may allow an acceptable alternative.
- Radiographic examination, when required, shall be performed on butt-welds in accordance with ASME B31.1 based on the piping system design pressure and shall be as follows:
Piping System Design Pressure Percentage 90 psig (621 kPa) or below Not Required 91 psig (627 kPa) to
150 psig (1034 kPa)
10 at Random Over 150 psig (1034 kPa) 100
However, if, in the opinion of the engineer responsible for special inspection, radiographic examination is not required for piping at pressure between 90 psig (621 kPa) and 150 psig (1034 kPa), the engineer shall so specify in writing, and the final report on the installation may omit the foregoing, and be predicated on all of the other requirements noted in this section, and a hydrostatic test.
The commissioner, where deemed necessary, shall require the replacement or relocation of any expansion joints, guides or anchors. The commissioner shall cause the expansion joints in potentially hazardous locations, such as those that are located adjacent to tenant occupied spaces, to be relocated, unless means exist or are provided for eliminating the hazard.