Labor & Industries (L&I), Washington State

Anhydrous Ammonia Chapter 296-826, WAC

Effective Date: 09/01/06

WAC 296-826-600 Operations

For printing

YOUR RESPONSIBILITY:

To protect employees while transporting, transferring, loading and unloading anhydrous ammonia

Mounting containers on trucks, semi-trailers and trailers	WAC 296-826-60005
Mounting containers on farm trucks or trailers for transporting ammonia	WAC 296-826-60010
Tank car loading or unloading	WAC 296-826-60015
TRANSFERRING LIQUIDS
General specifications	WAC 296-826-60020
Additional requirements for systems mounted on trucks, semi-trailers, and trailers for transporting ammonia	WAC 296-826-60025
FILLING DENSITIES
Nonrefrigerated containers	WAC 296-826-60030
Refrigerated tanks	WAC 296-826-60035
Welding	WAC 296-826-60040

 

WAC 296-826-60005

Mounting containers on trucks, semi-trailers and trailers

You must

• Make sure the method for attaching any container to the cradle, frame, or chassis of a vehicle is based on both of the following:
  • -Two "g" loading in either direction
  • -Using a safety factor of at least 4 based on the maximum strength of the material used.

Note: Two "g" is either of the following: -For load support it's equivalent to 3 times the static weight of the supported articles -For loading and bending, acceleration, and torsion it's equivalent to twice the static weight support applied horizontally at the road surface.

You must

• Secure both ends of the hose during transit.
• Follow the requirements in Table 14, Additional Container Mounting Requirements.

Table 14 Additional Container Mounting Requirements
If you have:	Then:
"Hold-down" devices	Anchor the container to the cradle, frame, or chassis so there's no area of unnecessary stress Lock the container down tightly Provide stops or anchors to minimize movement between the container and the framing Note:   Movement could be the result of stopping, starting or changing direction.
Vehicles with cargo tanks designed with stress members instead of a frame	Support the tank with external cradles suspended at least 120 degrees of the shell circumference The design calculation needs to include all of the following stressors: -Beam -Shear -Torsion -Bending moment -Acceleration -Any other stresses covered by the code of the cargo tank design.
A liquid withdrawal line installed in the bottom of a container	Then make sure the connections to the container, including the hose, aren't lower than the lowest horizontal edge of the trailer axle.
A cradle and container that aren't welded together	Use suitable material between them to eliminate metal-to-metal friction.

 

WAC 296-826-60010

Mounting containers on farm trucks or trailers for transporting ammonia

You must

• Make sure tanks mounted on farm trucks and trailers meet all of the following:
  • -Are securely attached using drawbars and safety chains
  • -Follow behind the towing vehicle without swerving
  • -Have at least 5 gallons of readily available clean water.
• Do all of the following when mounting containers on farm trucks:
  • -Use suitable material between the cradle and the container to eliminate metal-to-metal friction
    • This isn't necessary if the cradle and container are welded together
  • -Use stops and hold down devices to prevent displacement.
• Distribute the container's weight, when mounted on 4-wheel farm trucks or trailers, evenly over both axles.

WAC 296-826-60015

Tank car loading or unloading

You must

• Establish a location for tank car loading and unloading operations.
• Assign employees and instruct them in the unloading of tank cars.
• Make sure, when unloading cars, to set the brake and block the wheels.
• Make sure the track of tank siding is level.
• Place caution signs on the track or car to warn approaching persons of loading and unloading operations that are:
  • -Kept in place until the car is unloaded and disconnected from discharge connections.
• Make sure these caution signs meet all of the following:
  • -Are made of metal or other suitable material
  • -Are at least 12 to 15 inches in size
  • -Read either "Stop -Tank Car Connected" or "Stop Men
    at Work" meeting the following criteria:
    • "Stop" at least 4 inches high
    • All other words at least 2 inches high
    • All with white letters on a blue background.

TRANSFERRING LIQUIDS

WAC 296-826-60020

General specifications

You must

• Get owner authorization to use transfer containers.
• Make sure transfer containers are gauged and filled in either:
  • -Open atmospheres
  • or
  • -Buildings approved for that purpose.
• Make sure pumps used to transfer ammonia meet all of the following:
  • -Have a manufacturer's label for ammonia service
  • -Are designed for at least 250 psig working pressure
  • -Have a constant differential relief valve discharging into the suction port that:
    • Is installed on positive displacement pumps
      and
    • Meets the pump manufacturer's recommendation for the settings and installation
  • -Have a pressure gauge graduated zero to 400 psig installed on the discharge side before the relief valve line.
• Make sure plant pipes with shut off valves are located as close as possible to the pump connections.
• Make sure meters used for measuring liquid anhydrous ammonia:
  • -Are recommended and labeled for ammonia service by the manufacturer
  • -Are designed for a minimum working pressure of 250 psig
  • -Incorporate devices that prevent unintended measurement of vapor.
• Do the following when transferring ammonia:
  • -Maintain ammonia at a temperature suitable for the receiving container
  • -Have at least one attendant supervise the transfer from the time connections are made to when disconnection occurs
  • -Don't use flammable gases or gases that will react with ammonia, such as air to unload tank cars or transport trucks.
• Make sure compressors used for transferring ammonia meet all of the following:
  • -Have a working pressure of at least 250 psig when transferring ammonia.
  • -If crank cases of compressors aren't designed to withstand system pressure, then provide protection with a suitable safety relief valve
  • -Are connected to plant piping with shut off valves located as close as practical to compressor connections
  • -Have a safety relief valve that's both:
    • Large enough to discharge the full capacity of the compressor
      and
    • Connected to the discharge before any shut off valve
  • -Have an oil separator on the discharge side, where necessary to prevent contamination
  • -Have a drainable liquid trap or other adequate method on the compressor suction to minimize the entry of liquids into the compressor
  • -Pressure gauges on the suction and discharge ends graduated to at least one and one-half times the maximum pressure that can develop.
• Protect loading and unloading systems in the event of hose severance by suitable devices where necessary, such as:
• - Backflow check valves



or

• - Properly sized excess flow valves.

Note: If such valves aren't practical, remotely operated shut off valves may be installed.

WAC 296-826-60025

Additional requirements for systems mounted on trucks, semi-trailers, and trailers for transporting ammonia

You must

• Make sure the content of vehicle containers is determined by one of the following:
  • -Weight
  • -Liquid-level gauging devices
  • -Meters
    or
  • -Other approved methods.
• Use a thermometer well when the content of a container is determined by liquid-level measurement.   Make sure of the following:
  • -The volume, when converted to weight, doesn't exceed the DOT filling density requirement.
• Protect pumps and compressors against physical damage when mounted on trucks or trailers.
• Unload tank motor vehicles with a water capacity greater than 3,500 gallons at approved locations.

FILLING DENSITIES

WAC 296-826-60030

Nonrefrigerated containers

You must

• Make sure filling densities for nonrefrigerated containers are below or equal to the requirements in Table 15, Filling Densities.

Note: For uninsulated, aboveground containers, the 56% corresponds to: -82% by volume at -28° F -85% by volume at 5° F -87.5% by volume at 30° F -90.6% by volume at 60° F

WAC 296-826-60035

Refrigerated tanks

You must

• Make sure refrigerated tanks aren't liquid full at a liquid temperature so that the vapor pressure is below the "start-to-discharge" pressure setting of the safety relief valve.

WAC 296-826-60040

Welding

You must

• Permit welding only on the saddle plates, lugs, or brackets attached to the container by the manufacturer.