Receiving and Storage > Storage of Ammonia in Vessels
Sample piping and instrumentation diagram required by
the Process Safety Management standard
1910.119(d)(3)(i)(B) for a high pressure receiver.
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In some installations, ammonia is refrigerated and stored in low-pressure tanks. If ammonia is stored inside,
it is generally in a fire resistant structure, separated from work areas. It is important to keep storage areas dry and cool and away from steam pipes, heating devices, and tanks containing flammable liquids.
Ammonia stored outside in an uninsulated tank must be painted with reflective paint,
which controls rust or corrosion, and helps keep the temperature and internal pressure lower during hot weather.
| Storing Ammonia in Vessels |
Potential
Hazards
Figure 1. Pressure Vessels |
- Release of ammonia as a result of vessel failure due to:
- Improper design and installation (this can include improperly designed relief devices).
- Thermal expansion or contraction.
- Corrosion.
- Overfilling.
- External damage (for example, from a
forklift).
Possible Controls
- Provide information pertaining to
the hazards of ammonia. [1910.119(d)(1)]
- Design and install receiving/storage
vessels according to generally accepted good engineering practices.
[1910.119(d)(3)]
- Ensure that Safety Relief Valves
(SRVs) and relief systems for storage vessels are properly designed, installed in vapor space, and discharged to a safe location.
- Place barriers around receiving and storage vessels and other equipment to protect them from impact.
- Conduct a process hazard analysis. [1910.119(e)]
- Provide Operating Procedures [1910.119(f)] to ensure proper operation of
vessel, such as Standard Operating Procedures
(SOP) and Technical Operating Specifications
(TOS).
- See an example of a
High Pressure Receiver Vessel SOP.
- See Guidelines
for Writing Startup Procedures for additional information.
- The International Institute for Ammonia Refrigeration (IIAR) recommends developing TOS
that may include the following:
- Desired operating ranges for temperature, pressure, level, flow, and so on.
- Operating limits and consequences of deviation.
- Pertinent alarms, instruments and controls and their set points.
- Changes in operating controls and alarms during modes other than normal operation (start-up, shutdown, temporary operation,
and so on.)
- Safety devices associated with specific pieces of equipment or subsystems and their purpose and
set-point(s).
- Provide training specific to the operation of a receiver and storage vessel. [1910.119(g)]
- Maintain proper oxygen and water content in vessels to avoid stress corrosion cracking (SCC) in welds of vessels.
- Conduct a pre-startup safety review meeting prior
to introducing ammonia when the equipment is new
or modified significantly enough to require a
change in the process safety information. [1910.119(i)]
- Routinely inspect for corrosion of the receiving and storage vessel as part of a Mechanical Integrity Program. [1910.119(j)]
- Develop written procedures to
manually drain oil.
- See the Oil
Draining Guidelines listed in Additional Information below for procedures about safely draining oil from equipment.
- According to IIAR Bulletin No. 110, maintenance for pressure vessels should include the following tasks performed on a weekly basis:
- Check liquid level gauges for oil build up and drain if necessary.
- Drain oil from vessel (only on vessels where the opportunity for continuous entrance of oil exists). Some systems will be equipped with an automated oil recovery scheme. For those systems it is not necessary to manually drain oil from the
various vessels. It is however necessary that you periodically verify that the automated oil recovery system is functioning properly.
- Inspect vessel and insulation for external appearance and note any departures from normal appearance in the system log. The conditions under insulated portions of the system should be inspected on a periodic basis.
- Purge vessel of non-condensable gases. For those systems which operate under positive pressure, non-condensable gases are typically
introduced during improper maintenance (failure to evacuate after
opening the system) or improper charging procedures.
- Ensure that draining and venting plugs, caps, and blind flanges are in place and closed.
- Always pressure test any portion of the system opened for maintenance and before evacuation.
- Issue a hot work permit for hot work
operations conducted on or near the storage
vessel. [1910.119(k)]
- Establish and implement written procedures
to manage changes to equipment, procedures,
and facilities. [1910.119(l)]
- Investigate incidents. [1910.119(m)]
- Investigate accidents and near misses
that could have resulted in a release of
ammonia.
- Establish and implement an emergency action
plan in case of release. [1910.119(n)]
Additional Information
- Storage
Vessel Design. This document provides additional
information by ASME, ANSI, IIAR, and ASHRAE about the design and
installation of pressure vessels and associated
equipment.
- Oil
Draining Guidelines.
International Institute for Ammonia Refrigeration (IIAR) (2001, August), 1 page. This guideline describes procedures for safely draining oil from equipment.
- IIAR Process Safety Management Guidelines for Ammonia Refrigeration.
International Institute for Ammonia Refrigeration (IIAR) Ch. 6 (1998), 150 pages. This document contains more information
how to apply the OSHA PSM standard to Ammonia Refrigeration. See the Table of Contents.
- Bulletin No. 110. Guidelines for Start-Up, Inspection, and Maintenance of Ammonia Mechanical Refrigerating Systems.
International Institute for Ammonia Refrigeration (IIAR) (1993, March), 50 pages. See Appendix F - Pressure Tests for
procedures for pressure tests. See the Table of Contents.
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