Policy Recommendations: CSST Gas Piping Systems

The following codes are from the 1997 Regional Amendments and may not be the most current for all categories. 
For the newest list of codes and amendments, click here.

In an effort to continue with the process of supporting common codes across the Dallas/Fort Worth Metroplex and the North Central Texas Council of Governments planning region, the Plumbing and Mechanical Subcommittee of the Regional Codes Coordinating Committee undertook the review of issues dealing with corrugated stainless steel tubing (CSST) gas piping systems. Policy recommendations were developed in response to factors such as CSST being a relatively new product, a desire for more uniformity in CSST systems to facilitate inspection, safety concerns, and differing requirements among codes. Manufacturers participated throughout the policy formulation process, addressing committee member concerns, as they were able. Codes other than the 1997 International Plumbing Code were consulted and referenced when appropriate.

The issues and their solutions are as follows.

  1. Accessibility to Regulators

    1996 International Mechanical Code (IMC) Section 1307.1: Gas pressure regulators
    A gas pressure regulator or gas appliance pressure regulator shall be installed where the gas appliance is designed to operate at a lower pressure than the fuel gas system. Access shall be provided to pressure regulators. Pressure regulators shall be protected from physical damage. Regulators installed on the exterior of the building shall be approved for outdoor installation.

    Recommended Regional Policy: Access to regulators in an attic space shall meet the access requirements for furnaces and water heaters located in the attic (Section 306.3 of the IMC). A regulator must be within 20 feet of the attic access opening and served by an unobstructed passageway that is at least 30 inches high and 22 inches wide. However, larger access is required to accommodate the largest piece of equipment if that piece of equipment will not fit through the 30 inch by 22 inch passageway. The passageway must have continuous and solid flooring not less than 24 inches wide. A level service space of 30 inches deep and 30 inches wide must be provided at the front or service side of the appliance. Exception: a passageway or level service space is not required when the appliance is capable of being serviced and removed through the required attic opening.

  2. Method of System Tagging for Medium Pressure Lines

    IMC Section 1301.5. and 1997 International Plumbing Code (IPC) Section G101.5 
    Identification: For other than black steel pipe, exposed gas piping shall be identified by a yellow label marked "Gas" in black letters. The marking shall be spaced at intervals not exceeding 5 feet (1524 mm). The marking shall not be required on pipe located in the same room as the equipment served. All tubing carrying medium-pressure gas shall be marked with a label at the beginning and end of each tubing section.

    Recommended Regional Policy: Both ends of each section of medium pressure corrugated stainless steel tubing (CSST) shall identify its operating gas pressure with an approved tag. The tags are to be composed of aluminum or stainless steel and the following wording shall be stamped into the tag.

    ½ to 5 psi gas pressure
    Do Not Remove

  3. Valve Security/Support

    IMC Section 1305.5. and IPC Section G105.5: Accessibility of gas valves
    Shutoff valves controlling separate piping systems shall be placed an adequate distance from each other so they will be readily accessible for operation and shall be installed so as to be protected from damage. Shutoff valves shall be plainly marked with an identification tag attached by the installer so that the piping systems supplied by such valves are readily identified.

    Recommended Regional Policy: Shutoff valves installed in corrugated stainless steel tubing (CSST) gas piping systems shall be supported with an approved termination fitting, or equivalent support, suitable for the size of the valves, of adequate strength and quality, and located at intervals so as to prevent or damp out excessive vibration but in no case greater than 12-inches from the center of the valve. Supports shall be installed so as not to interfere with the free expansion and contraction of the system’s piping, fittings, and valves between anchors. All valves and supports shall be designed and installed so they will not be disengaged by movement of the supported piping.

  4. Concealed Fittings

    IMC Section 1304.3. and IPC Section G104.3: Piping in concealed locations. 
    Portions of a gas piping system installed in concealed locations shall not have unions, tubing fittings or running threads.

    Recommended Regional Policy: In order to maintain consistency in the North Texas Region and to stay abreast with changing technologies it is recommended that listed fittings for concealed locations be approved. The 1997 International Gas Code recognizes and permits the use of gas fittings listed for use in concealed locations. Therefore, it is recommended that the 1997 International Gas Code Section 404.3 be recognized as a policy change to the International Mechanical & Plumbing Codes Sections 1304.3 and G104.3, respectively. The 1997 International Gas Code reads as follows.

    404.3 Piping in Concealed Locations. Portions of a gas piping system installed in concealed locations shall not have unions, tubing fittings, right and left couplings, bushings, compression couplings and swing joints made by combinations of fittings.

    • Tubing joined by brazing
    • Fittings listed for use in concealed locations

    Since couplings are listed for use in concealed locations, no limitations will be made regarding the use of couplings within a stud wall space.

  5. Island Gas Ranges

    IMC Section 1304.7: Piping in Solid Floors
    Piping shall not be installed in solid floor slabs, such as concrete or masonry, except where the code official determines that there is no other practical manner of installing such piping. For this type of floor construction, the house piping shall be installed above the floor, in an open or furred space, hollow partition, hollow wall, attic space or pipe chase.

    Recommended Regional Policy: Island gas ranges will be installed according to particular corrugated stainless steel tubing manufacturer recommendations and installation manual with the following additional requirements.

    • Chases must be sealed with a non-gas-permeable expandable foam sealant.
    • The line must be vented to the outside, with the bottom of the down-turned vent measuring no less than twelve inches above grade.
    • The gas line must be anchored with termination fittings within twelve inches of the point where the line penetrates the floor underneath the gas range.

    Reference drawings for Ward Flex recommendations and Gastite recommendations are available from NCTCOG staff.

The North Central Texas Council of Governments, upon the recommendation of the Regional Codes Coordinating Committee and its Plumbing and Mechanical Subcommittee, encourages your jurisdiction to implement the recommended policies as detailed above to enhance your enforcement of code provisions and purposes.