One of my all time favorite RAGAGEPs is the Compressed Gas Association’s (CGA) 2.1 for those who handle anhydrous ammonia. This year, they published the 7th Edition, and they made it even better. Unlike so many RAGAGEPs, the CGA embraced the practice of “Continuous improvement” and really did a nice job with their additional explanations of their existing requirements. It almost seems they were sitting on my shoulder during some of our audits over the past nine years. Here are some of my favorite revisions and additions to the 2023 edition.
- Pressure Testing and Leak Testing Piping
- Hose Testing
- Hydrostatic Relief Valves
- Transfer of ammonia
- Electrical equipment and wiring
- Emergency Shutoff Valves
Pressure testing and Leak Testing Piping
In the 2014 edition, this is what it said regarding complying with ASME B31.3
5.6.8 After assembly, all piping, fittings, and tubing shall be tested and proved to be free from leaks at a pressure specified by ASME B31.3 or ASME 831.5 as appropriate [38. 39]. Underground piping shall be evaluated at a minimum of every 5 years to ensure leak-tightness.
In the 2023 edition, this is how they stated it:
5.6.9 After assembly of piping or tubing, not including appurtenances that have joints connected by welding, field threading of pipe (i.e., nonfactory threads), or other methods, joints shall be pressure tested to either at least 1.1 times for pneumatic (air or nitrogen) or 1.5 times for hydrostatic of the MAWP and maintained for a period of
time sufficient to equalize piping strains.
5.6.10 After assembly of the complete piping system, including appurtenances and components, the piping system shall be proven free of leaks by performing a leak test at not less than the normal operating pressure of the system. Using anhydrous ammonia as a test medium shall be permitted.
5.6.11 Underground piping shall be protected and maintained against external corrosion. Underground piping shall be leak tested at least every 5 years in accordance with 5.6.10.
Now, that last part (highlighted in red bold), where the standard states that “using anhydrous ammonia as a test medium shall be permitted,” is a MAJOR MISS on CGA’s part. I know of no RAGAGEP that permits a “toxic” such as NH3 to be used to pressure or leak test piping. ASME and the IFC, expressly PROHIBIT toxics and flammables, from being used. In my training courses, I use the phrase “farmers test” when discussing leak and pressure testing using NH3. It may be acceptable on a tiny process such as those used by farmers in the middle of a 1,000-acre corn field, but fixed facilities will have MUCH SAFER options for its test pressure and leaking testing media.
Hose Testing (emphasis by me)
5.7.10 Annual pressure requalification test
Hoses used in ammonia service shall be pressure tested at least annually.
The pressure test requirement does not apply to:
- hoses installed as a fixed component of a process, for example, hoses that are not removed or reattached at either end routinely as part of normal operations such as flexible metal pipe connectors (see 5.6.6);
- implements of husbandry with respect to filling and field application; however, pressure testing should be considered for these operations; and
- hoses used in ammonia service that have a MAWP of 2000 psi (13 790 kPa) or greater and a burst pressure of at least 4 times the MAWP.
5.7.10.1 General
Hoses may be pressure tested either pneumatically or hydrostatically. Pressure testing, following the precautions described in 5.7.10.2, should only be performed by qualified personnel.
In either of the pressure test methods described in 5.7.10.1.1 and 5.7.10.1.2, the hose shall be tested at ambient temperature, lying flat and straight, with one end of the hose connected to a pressure source that includes an accurate test pressure gauge that has been calibrated within the past one year and a blowdown valve. The test pressure shall be gradually increased until the maximum test pressure is reached as specified in 5.7.10.1.1 or 5.7.10.1.2, depending on the test method used. Do not exceed the specified test pressure. To pass the pressure test, the hose shall be pressure tight and without decay for at least 1 minute. If the braid wires start to break or the hose starts to deform during the pressurization of the hose, the blowdown valve shall be opened immediately to depressurize the hose. Any observable leaks, bulges, or other defects shall disqualify the hose from, continued use until the defects are repaired in accordance with 5.7.12. The working pressure of the hose assembly includes the hose as well as any attached couplings.
5.7.10.1.1 Hydrostatic test
When conducting a hydrostatic test, ensure the corrugations of the hose inner core are completely filled with water to displace any air. This is accomplished by positioning the hose at a slope and filling it with water from the bottom while flexing sections of the hose to a vertical position and shaking the hose to dislodge any air that is contained In the corrugations. This allows the air to escape from the elevated end of the hose. The hose shall be hydrostatically tested at 1.5 times the MAWP. The pressure should be raised slowly and incrementally, but not lo exceed 50 psi (340 kPa) per minute. The inside of the hose should be dried after testing.
5.7.10.1.2 Pneumatic pressure test
The pneumatic pressure test may be conducted with dry nitrogen gas or dry, oil-free compressed air. The hose shall be pressurized gradually to a test pressure of 1.1 times the MAWP. The pressure should be raised slowly and incrementally but not to exceed 50 psi (340 kPa) per minute. After remaining at the test pressure for 1 minute, reduce the pressure to MAWP (or 90% MAWP). The hose may be checked for leaks with either of the following methods:
- Using an oxygen compatible leak check solution applied to the outside of the hose to check for leaks along the entire length outer circumference and at the end fittings. Leaks are indicated by the formation of bubbles.
or - Submerging the entire hose under water after the outside of the hose is shaken free of any retained air. The hose shall be observed for the discharge of any gas or air bubbles for at least 1 minute.
5.7.10.2 Precautions
Ensure personnel safety and protect property from damage during pressure testing as follows :
- Secure the hose along its length to allow free movement, but do not allow whipping , hose extension, or the release of particulates toward test personnel in the case of failure:
- Contain or orient ends of the hose so a blowout fitting does not cause injury or damage ;
- Provide personnel with protection against the force of the pressure medium if failure occurs . This protection shall include safety eyewear.
- Establish a safe zone around the test area to protect person nel from injury in case of hose failure. Personnel shall not be allowed in line with the hose ends during a pressure test: and
- Adequately protect the pressure test set-up against any overpressure (43).
5.7.10.3
For continued service, each hose assembly shall be marked or tagged with the date of qualification resulting from repair and pressure testing. The qualification date (month/year) indicating an acceptable pressure test shall be durably marked on the hose, preferably at one of the ends. The hose MAWP shall be legibly marked on the hose assembly for future inspection purposes. Documentation of the qualification of the hose shall be retained by the company testing the hose and by the company using the hose.
Hydrostatic Relief Valves (emphasis by me)
5.8.2.1
A hydrostatic relief valve or equivalent shall be installed in each section of piping (including hose) in which liquid ammonia can be isolated between shutoff valves to relieve the pressure that could develop from the trapped liquid. If an equivalent pressure relieving device is used, the maximum accumulative pressure possible within the system shall not exceed the limits of the system.
A facility operating in the United States under 29 CFR 1910.119 Process Safety Management 01 in Canada, under the Canadian equivalent, may modify the requirement for a hydrostatic relief valve based on possible trapped line volume by technical analysis using methods and analysis in accordance with a recognized and generally accepted engineering approach (In no case shall the possible trapped volume of a line without hydrostatic relief valve protection exceed 26.4 gallons (100 liters).
5.8.2.2
The discharge from hydrostatic relief valves shall be vented to a safe location. The hydrostatic relief valve shall be protected from ingress of moisture, bugs, dirt, debris, etc. For example, a rain cap or other means that allows the hydrostatic relief valve to function properly.
5.8.2.3
Shutoff valves shall not be installed between a hydrostatic relief valve and the system it protects. To allow for maintenance of a hydrostatic relief valve while the system is in service an isolation device may be installed provided that the piping circuit remains protected from overpressure. For example, a three-way valve with two hydrostatic relief valves installed in the valve that results in one hydrostatic relief valve always being in contact with the protected system may be used.
5.8.2.4
Each hydrostatic relief valve shall be plainly and permanently marked as follows with:
- letters “AA” or the symbol “NH,”;
- pressure in psi at which the valve is set to start-to-discharge;
- month and year of manufacture; and
- manufacturer’s name, symbol or model number.
5.8.2.5
A hydrostatic relief valve shall be subject to a systematic, periodic, visual external inspection at least annually to determine that it:
- meets the applicable requirements specified in 5.8.2
- is free of evidence of tampering, damage, corrosion or foreign matter that could prevent proper operation:
- is free of leakage when subject to pressures less than the minimum allowable start-to-discharge setting: and
- has a properly installed rain cap or other means to avoid entry of moisture or other matter into the relief valve outlet.
5.8.2.6
Any deficiency found in 5 8.2.5 shall require immediate corrective action replacement or repair of the hydrostatic relief valve as appropriate. If a hydrostatic relief valve activates, it should be evaluated to determine suitability for continued use.
5.8.2.7
No hydrostatic relief valve shall be used after the replacement date as specified by the manufacturer of the device. If no date is specified, a hydrostatic relief valve shall be replaced no later than 5 years following the date of its manufacture or last repair unless it has first been disassembled, inspected, repaired, and tested by the manufacturer or by an accredited valve repair organization so that the valve’s condition and performance is certified as being equivalent to the standards for the original valve. The data regarding repairs or reassembly shall be indicated by stamping the body or attaching a tag pertaining to the valve with the month and year to replace or recertify. Example. 4/01
Transfer of ammonia (emphasis by me)
This section applies to hose, piping, and fittings greater than 2 ft in length or greater than 3 In ID:
- Anhydrous ammonia should be vented to a safe location such as an adequate supply of water (see 4.4.1 ), to a properly designed atmospheric discharge point, flare, etc., and
- A water container used for venting anhydrous ammonia shall be properly designed to prevent the container from being overpressurized.
5.10.10.1
Each cargo tank motor vehicle unloading point at an anhydrous ammonia storage site shall have a valve for the purpose of venting ammonia installed In the piping at or near the point where the piping and hose from the cargo tank motor vehicle are connected.
5.10.10.2
The ammonia should be injected into the water as near the bottom of the vessel as practical. See 4.4.1.
5.10.10.3
Any aqueous ammonia solution resulting from the venting process shall be reprocessed, recycled, used, or disposed of safely and properly.
Electrical equipment and wiring
Where concentrations of ammonia in air in excess of 16% by volume are expected to be present during normal operations, electrical equipment, and wiring shall be installed to comply with the requirements specified for use in hazardous locations, Class I, Group D of NFPA 70, National Electrical Code®, Articles 500 and 501.
Emergency Shutoff Valves (emphasis by me)
6.2.2
In addition to the minimum protection, installation of emergency shutoff valves may be considered. This can be accomplished by either actuation of an internal valve or the addition of a separate emergency shutoff valve located within 10 lineal ft (3 lineal m) of the opening side of the manual shutoff valve.
If an emergency shutoff valve is installed, the following requirements shall be met:
- Approved emergency shutoff valves or internal valves shall incorporate a reliable actuation system (for example, electrical, pressure, or cable) that closes all of the emergency shutoff valves or internal valves of the piping system on the first attempt in the event of emergency or of testing from a remote location. There shall be a minimum of two remote actuation locations reasonably opposite to each other; and
- If using a pressure source for activation of the emergency shutoff valves or internal valves, nitrogen, compressed air, or carbon dioxide is deemed acceptable. If using compressed air as a pressure source, the air shall be clean and kept at a moisture level that does not prevent the system from operating. Propane or other flammable materials shall be prohibited for use to activate an emergency shutoff valve or an internal valve.
Actuation systems should be tested annually for the functions required.
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