WAC 296-826-50020   Systems mounted on trucks, semi-trailers and trailers.  

     IMPORTANT:

     In addition to this section, you need to follow the Appurtenances requirements for all systems, WAC 296-826-50005.

     You must:

     • Make sure each container has all of the following

     – Fixed maximum liquid level gauging devices

     – Pressure-indicator gauges with a dial graduated from zero to 400 psig

     – Either of the following:

     ▪ Equipped for spray-loading, which fills in vapor space;

     OR

     ▪ Has an approved vapor return valve of adequate capacity.

     • Provide one or more spring-loaded safety relief valves, or an equivalent type, on all containers, that do all of the following:

     – Discharges in the following ways:

     ▪ Away from the container in an upward, unobstructed manner into the atmosphere

     ▪ Not in or beneath a building.

     – Has raincaps that allow free discharge of the vapor and prevent the entrance of water

     – Has a method for draining accumulated condensation

     – Has a start to discharge, related to the design pressure of the container, according to Table 6, Safety Valve Start to Discharge Rate

     – Are arranged to minimize the possibility of tampering

     – Provided, when the pressure setting adjustment is external, with a means of sealing the adjustment

     – Has direct communication with the vapor space of the container

     • Make sure shut off valves are not installed between the safety relief valve and the container or system. A shut off valve may be used if arranged so that the required capacity flow is maintained.

Exemption: • You are exempt from the requirement not to install the shut off valve between the safety relief valve and the container or systems in the following situations:
– A three-way valve installed under two safety relief valves, each with
▪ The required rate of discharge;
AND
▪ Installed to allow either of the safety relief valves to be closed off but not at the same time.
– Two separate relief valves are installed with individual shut off valves.
▪ The two shut off valve stems must be mechanically interconnected to allow the full required flow of one safety relief valve at all times.
– When a safety relief valve manifold that allows:
▪ One valve of two or more to be closed off
AND
▪ The remaining valve or valves will provide not less than the rate of discharge shown on the manifold nameplate.

     • Follow additional requirements found in Table 11, Appurtenances for Systems Mounted on Trucks, Semi-Trailers and Trailers


Table 11

Appurtenances for Systems Mounted on Trucks, Semi-Trailers and Trailers
If you have: Then make sure they:
All container connections Are provided with either of the following:
Automatic excess flow valves;
OR
Quick-closing internal valves that remain closed except during delivery operations
Note: If the control mechanism is provided with a secondary control remote from the delivery connection, then a fusible section (melting point 208°F to 220°F) is required to permit the internal valve to close automatically in case of fire.
  Exemption: Filling connections, safety relief devices, and liquid level and pressure gauge connections are exempt from automatic excess flow valves and quick-closing internal valves.
Filling connections Prevent back-flow in the event the filling connection breaks with at least one of the following:
• Automatic back pressure check valves
• Excess flow check valves
• Quick closing internal valves
Exemption:
• An automatic valve is not required if:
– The filling and discharge connect to a common opening in the container shell;
AND
  – The opening is fitted with a quick-closing internal valve
Nonrecessed container fittings and appurtenances Are protected against physical damage by one of the following methods:
• A protected location
• The vehicle frame or bumper
• A protective housing that meets the following:
– Is fabricated from material that is compatible with the containers design and construction requirements
– Designed to withstand static loadings in any direction equal to twice the weight of the container and attachments when filled using a safety factor of not less than 4, based on the ultimate strength of the material used
  Note: Protect nonrecessed container fittings and appurtenances with a weather cover as needed for proper operation of valves and safety relief devices
Columnar-type gauges Are restricted to stationary storage installations
Are shielded against the direct rays of the sun
Are equipped with all of the following:
– Shut off valves having metallic hand-wheels
– Excess flow valves
  – Extra heavy glass that is adequately protected with a metal housing applied by the gauge manufacturer
Hydrostatic relief valves Are installed between each pair of valves in the liquid ammonia piping or hose.




[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, 49.17.060. 06-10-067, § 296-826-50020, filed 5/2/06, effective 9/1/06.]