Comparison of Pressure Vessel Inspection Requirements in Refrigeration Industry

Comparison of Pressure Vessel Inspection Requirements in the Refrigeration Industry
Code	Type of Inspection	Component Description	Inspection	Remediation	Inspection Frequency
IIAR 109 (1997)		All pressure vessels	If signs of more than mild corrosion should inspect further by a professional engineer or ASME inspector (4.3.5)	None listed	– Annual ammonia safety check (5.2) – Thorough inspection every 5 years (5.3)
IIAR 110 (1993) Including (2004 addenda)	Routine Operational Maintenance (6.4.2.1)	Uninsulated vessels	External surface appearance should be regularly checked for deterioration.	The deterioration that is found should be repaired.	Along with the operator’s routine activities.
	Routine Operational Maintenance (6.4.2.1)	Insulated vessels	The surface of the insulation should be regularly checked for deterioration.	The deterioration that is found should be repaired.	Along with the operator’s routine activities.
	Annual Inspection (6.4.3.1)	Uninsulated vessels	The external surface should be inspected.	– If the vapor barrier is intact, no further action (insulated). – Where insulation is damaged, inspect/clean the pipe and reapply insulation and vapor barrier (insulated). – If large material loss, deal in accordance with section 6.4.4: Independent Inspection	No less than every 12 months.
	Annual Inspection (6.4.3.1)	Insulated vessels	Insulation and vapor barrier should be inspected.		No less than every 12 months.
	Independent Inspection (6.4.4)	Uninsulated vessels	The external surface should be inspected.	– No indication of deterioration; no action. – Surface corrosion that doesn’t alter thickness; clean and repaint. – External corrosion reducing thickness; measure the thickness to determine if replacement is necessary.	At least once every 5 years.
	Independent Inspection (6.4.4)	Insulated vessels	Insulation and vapor barrier should be inspected.	– Wet insulation was removed, and the surface below was inspected. Treat with rust preventative and reinsulate. – If insulation is unsound or damaged, remove and inspect the surface in accordance with 6.4.4.2.	At least once every 5 years.
Code	Type of Inspection	Component Description	Inspection	Remediation	Inspection Frequency
NBIC – 23	External Inspection (RB-3231)	General Pressure Vessel, Insulated	Removal is unnecessary if insulation and corrosion-resistant linings are in good condition. Advisable to remove small portions.		The maximum period between internal inspections or a complete on-stream evaluation of pressure vessels shall not exceed one-half of the estimated remaining life of the vessel or ten years, whichever is less. When the remaining operating life is less than four years, the inspection interval may be the full remaining safe operating life up to a maximum of two years.
	External Inspection (RB-3231)	General Pressure Vessel	The surface must be inspected for erosion, dents, distortion, cuts, gouges, bulges, blisters, corrosion or other deterioration. Welds are also to be inspected.
	Internal Inspection (RB-3232)	General visual inspection for corrosion, erosion, deformation, cracking, and laminations Welds, nozzles, liquid level lines, and areas opposite inlet nozzles were carefully inspected for corrosion.
	Liquid Ammonia Vessels (RB-3700)	Internal Inspection (RB-3740)	-Visual internal inspection looking for obvious cracks (advanced SCC) -“It is not intended that the vessel provides for access. It is understood that internal inspections will be made if the vessel has access to the internal surfaces.	-If cracks are discovered, calculate the depth of grinding that may be carried out for crack removal. (Keep minimum wall thickness in mind.) -Where possible, remove the crack by grinding. -Re-inspect by WFMT to ensure removal. Acoustic emission and fracture mechanics are also acceptable. -Weld repair for deeper cracks.
Code	Type of Inspection	Component Description	Inspection	Remediation	Inspection Frequency
API 510	External Visual Inspection	All pressure vessels	External visual inspection to determine condition of vessel, exterior insulation, supports and signs of leakage.	If distortion or defect observed, further testing is warranted by other NDT method.
	Corrosion Under Insulation Inspection	Insulated Vessels	CUI inspection considered for vessels that operate between 25°F and 250°F or intermittently. This may require insulation removal.	Repair or replace following the requirements of ASME codes, the code to which the vessel was built or other specific pressure vessel rating codes.
	Vessel Insulation	Vessels with over 10 yrs remaining life that are protected from external corrosion	Insulation does not need to be removed for inspection, but insulation/outer jacket should be inspected.	Repair damaged insulation/outer jacket.
	Internal Inspection	All vessels	Internal inspection of on-stream inspection. On-stream inspection is the use of NDE procedures external to vessel.	Repair or replace following the requirements of ASME codes, the code to which the vessel was built or other specific pressure vessel rating codes.	Not to exceed the less of ½ of estimated remaining life based on corrosion rate or 10 years.
	Corrosion Rate Determination	All vessels	Measurements to be taken by NDT methods, measurements at suitable openings or gauging of uncorroded surfaces next to corroded surfaces. A representative number of measurements to be taken on all major components, sample of nozzles and other appropriate areas of concern.		A. Calculated from vessels in same service B. Estimated from experience or published data C. Measurements taken every 1000 operating hours until rate determined.
Source: IRC Mechanical Integrity Workshop

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