AR · Expiry & renewal tracking
Never let the yearly ultrasonic check of refrigerant vessels lapse
At industrial sites in Buenos Aires Province, pressure vessels holding ammonia, freon or other refrigerants need a yearly ultrasonic thickness check, after which the vapour barrier is restored (Resolution 231/96, Article 89, as worded by Resolution 1126/07). Tests are done by licensed engineers.
Resolution 231/96 of the then Secretariat for Environmental Policy of Buenos Aires Province regulates pressure equipment installed in establishments covered by Industrial Siting Law 11,459, including vessels and installations for liquid refrigerants (recitals). As worded by Resolution 1126/07, unfired pressure equipment means vessels with a minimum volume of 80 litres and/or a minimum gauge working pressure of 3 kg/cm² (Article 1), and the tanks of refrigeration system equipment are grouped among unfired pressure vessels (Article 33(e)). The current implementing rules of Law 11,459, Decree 531/19, keep the enforcing authority's power to regulate pressure equipment (Annex, Article 26), and the provincial Ministry of Environment still applies Resolution 231/96 with its amendment 1126/07 in its 2026 enforcement decisions.
For vessels containing refrigerants such as ammonia or freon, an ultrasonic thickness check is carried out every year, after which the vapour barrier is restored (Resolution 231/96, Article 89, as worded by Resolution 1126/07, Article 16). Equipment containing ammonia is licensed with a hydraulic test at 1.5 times the working pressure; every 8 years all insulation is removed and a thorough ultrasonic study is made, with a hydraulic test at design pressure if faults are found or repairs are needed; and from licensing onwards, an ultrasonic thickness verification at fixed points is made every year (Article 88, as worded by Resolution 1126/07, Article 15). Non-destructive tests and checks of safety devices are carried out at the intervals in Appendix 1 by engineers licensed by the enforcing authority (Article 11, as worded by Resolution 1126/07, Article 3).
The enforcing authority may allow the expiry dates of the registrations to be moved so that inspections coincide with scheduled plant shutdowns: the establishment must request this with a technical report signed by a licensed engineer and submit its schedule at least 60 calendar days before the work or the original expiry dates, whichever is earlier; the schedule is deemed approved if no observations are made within 20 calendar days, and the registrations remain valid until the new date (Article 11). Any installation producing cold with refrigerants must be attended permanently by a specially trained operator, under the company's responsibility (Article 86, as worded by Resolution 1126/07, Article 14).
At a glance
| Ultrasonic thickness check | Yearly, on vessels holding ammonia, freon or other refrigerants, then restoring the vapour barrier (Resolution 231/96, Article 89, as worded by Resolution 1126/07) |
|---|---|
| Thickness verification at fixed points | Yearly from licensing, on ammonia equipment (Article 88, as worded by Resolution 1126/07) |
| Thorough ultrasonic study | Every 8 years, removing all insulation, on ammonia equipment (Article 88) |
| Licensing of ammonia equipment | Hydraulic test at 1.5 times the working pressure (Article 88) |
| Unfired pressure equipment threshold | Minimum volume 80 litres and/or minimum working pressure 3 kg/cm² (Article 1, as worded by Resolution 1126/07) |
| Who tests | Engineers licensed by the enforcing authority (Article 11) |
| Moving dates for plant shutdowns | Request 60 calendar days in advance; approved if no observations within 20 days (Article 11) |
A Buenos Aires Province rule for establishments covered by Law 11,459; Buenos Aires City and the other provinces have their own regimes. Resolution 231/96 was issued under Decree 1741/96, since repealed by Decree 531/19, which keeps the power to regulate pressure equipment (Annex, Article 26); the Ministry of Environment's 2026 enforcement decisions still apply it together with Resolution 1126/07. The inspection schedule in the current version of Appendix 1 could not be read as text; the intervals in this guide come from Articles 88 and 89.
Who is responsible?
The owner or operator of the industrial establishment must have its vessels tested periodically, at its own expense, and keep the licensing registrations valid (Resolution 231/96, Articles 11 and 14, as worded by Resolution 1126/07). The tests are performed by engineers listed in the enforcing authority's register, who record the results in inspection reports with the status of a sworn statement and deliver them within 60 calendar days of the test (Appendix 1, points 3.3 and 3.4). The enforcing authority for Law 11,459 is now the Ministry of Environment of Buenos Aires Province, acting through its pressure equipment unit.
If the deadline passes
If the engineer finds defects that lead to imminent risk, they must take the equipment out of service on their own responsibility and inform the enforcing authority within 72 hours (Resolution 231/96, Appendix 1, point 3.5, as worded by Resolution 1126/07). Lack of licensing or of verification, test and safety-device check reports for pressure equipment is charged as a breach of Article 11 of Resolution 231/96 and allows the preventive closure, total or partial, of the establishment or the equipment for serious risk of imminent harm (Decree 531/19, Annex, Article 20(ii)), a measure the provincial Ministry of Environment applied and confirmed in 2026 decisions. Breaches of Law 11,459 are also punished by a warning, a fine or closure (Law 11,459, Article 17).
A yearly deadline and another every eight years
Ammonia equipment follows two cycles: the yearly ultrasonic thickness verification at fixed points and, every 8 years, the thorough study with full removal of insulation (Resolution 231/96, Article 88, as worded by Resolution 1126/07). Other refrigerant vessels follow the yearly ultrasonic check in Article 89. If the plant has scheduled shutdowns, the request to align the dates must be filed at least 60 calendar days in advance (Article 11).
Tracking it with ExpirySuite
- Add each refrigerant vessel or unit and record the expiry date of its licensing registration or of the last ultrasonic thickness check; you can add the 8-year thorough study as a separate record.
- Email reminders arrive 60, 30, 14, 7 and 1 day before expiry and on the expiry day; the first reminder matches the 60 calendar days the rules set for requesting date changes for plant shutdowns.
- The licensed engineer can upload the inspection report or the new registration through a secure link that is valid for 14 days and needs no account.
- Assign a responsible person, such as the maintenance manager; if a check expires, managers get further reminders 3, 7 and 14 days later.
Frequently asked questions
- How often is the ultrasonic check done?
- Every year, on vessels containing refrigerants such as ammonia or freon, after which the vapour barrier is restored (Resolution 231/96, Article 89, as worded by Resolution 1126/07, Article 16). Ammonia equipment also needs, every 8 years, a thorough ultrasonic study with full removal of insulation (Article 88).
- Which vessels are covered?
- Pressure equipment installed in establishments covered by Law 11,459. As worded by Resolution 1126/07, unfired equipment means vessels with a minimum volume of 80 litres and/or a minimum working pressure of 3 kg/cm² (Article 1), and the tanks of refrigeration system equipment are included among unfired pressure vessels (Article 33(e)).
- Who may perform the tests?
- Engineers licensed by the enforcing authority and listed in its register; Level B, required for remaining-life tests, calls for ultrasonic thickness measuring equipment (Resolution 231/96, Article 113 and Appendix 1, point 2, as worded by Resolution 1126/07).
- Can the dates be moved to match a plant shutdown?
- Yes, with the enforcing authority's approval. The establishment files a technical report signed by a licensed engineer and its schedule at least 60 calendar days in advance; if no observations are made within 20 calendar days, the schedule is deemed approved and the registrations remain valid until the new date (Resolution 231/96, Article 11, as worded by Resolution 1126/07).
Sources
- Resolución SPA 231/96, Aparatos Sometidos a Presión, texto original, artículos 1, 11, 86 a 91 y Apéndice 1 (Ministerio de Ambiente, Provincia de Buenos Aires)
- Resolución SPA 1126/07, modificatoria de la Resolución 231/96, artículos 1, 3, 8, 14 a 16, 24 y 27 (normas.gba.gob.ar)
- Ley 11.459, texto actualizado, artículos 1, 17 y 20 (normas.gba.gob.ar)
- Decreto 531/19, reglamentación de la Ley 11.459, texto actualizado, Anexo, artículos 20 y 26 (normas.gba.gob.ar)
- Disposición de la Dirección Provincial de Control y Fiscalización, Ministerio de Ambiente, 2026: clausura preventiva por aparato a presión sin habilitación ni ensayos (Resolución 231/96, artículo 11)
Last checked: Oct 11, 2026 · This page summarises official sources for general information and is not legal advice. Check the linked sources for current rules and fees.
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