SSPC-PA 2-2022 Explained

The bottom line

SSPC-PA 2-2022 turns “is the coating thickness acceptable” into a reproducible calculation: it specifies how many areas and spots to measure, how many readings make a spot, and the spot and area limits for acceptance. Follow the procedure and different inspectors should reach the same conclusion.

Document identity

Item	Content
Number	SSPC-PA 2-2022
Document type	Procedure
Issuing body	AMPP (formed by the 2021 merger of SSPC and NACE International)
Previous editions	Previous revisions: 2015, 2012, 2004, 1996 and 1982; first issued in 1973.
Length	The 2022 edition contains 11 appendices; refer to the edition specified by the contract.
Companion standard	Must be used together with ASTM D7091-22
Instrument class	Follows the D7091 Type 1 / Type 2 definitions

Core 1: spot count table

Coated area	Number of spot measurements
≤ 30 m² (300 ft²)	5 in every 10 m² (100 ft²) area
30–100 m² (300–1000 ft²)	15 (5 in each of three 10 m² areas)
> 100 m² (1000 ft²): first 100 m²	15 (three 10 m² areas, as above)
Each additional 100 m² (1000 ft²) or part	5 more (one more 10 m² area)

Each spot measurement is not a single reading, but the average of at least 3 readings taken within a ~1.5 inch diameter area. This design uses local repeated measurement to suppress random error and makes the spot average more reliable.

Core 2: the acceptance rule (Level 3 by default)

SSPC-PA 2 does not use the 80/20 rule (that belongs to ISO 19840). It sets restriction levels; at Level 3, the default, these conditions apply:

Each spot measurement (the average of at least 3 gauge readings) ≥ 80 % of the specified minimum and ≤ 120 % of the specified maximum;
Each area measurement (the average of 5 spots) falls within the specified minimum–maximum range;
Individual gauge readings are not restricted at Level 3; they are averaged into the spot.

If either limit is not met, the area is judged non-conforming. Projects to ISO 19840 use the 80/20 rule instead — see the“80/20 Rule”article in this section for a worked example.

The appendices: referenced selectively by contract

Annex	Content
Annex 1	Examples of average thickness measurement and determination of non-conforming area size
Annex 2	Thickness measurement of steel girders
Annex 3	Measurement after shop painting of steel girders, structural steel and miscellaneous items
Annex 4	Measurement method for coating test plates
Annex 5	Measurement of thin coatings after abrasive blasting
Annex 6	Edge coating thickness measurement
Annex 7	Thickness measurement of coated steel pipe exterior
Annex 8	Example of Type 2 instrument shim adjustment
Annex 9	Notes on coating failure investigation
Annex 10	Type 2 instrument continuous scan / scanning probe technique
Annex 11	Thickness measurement of intumescent fireproofing and cryogenic spill protection coatings on structural steel, fire divisions, pipework and vessels/tanks

Applicable instruments

PA 2 references the D7091 instrument classification in its clauses: Type 1 magnetic pull-off and Type 2 electronic. Current engineering practice is dominated by Type 2; all Dongru coating thickness gauges belong to this class.

Corresponding models in the Dongru product line

The common nominal thickness range for steel anti-corrosion determines model selection: for conventional coating (~100-400 μm) use DR280A (0-1250 μm, dual mode) or DR360A (0-2000 μm); for heavy anti-corrosion and thick coatings use DR380A (0-2000 μm) or DR6000A (0-6000 μm).

Common misconceptions

❌ “PA 2 only applies to US projects” — European projects commonly use ISO 19840, whose sampling plan and 80/20 rule differ from PA 2’s spot-and-area limits; for cross-region work follow the contract designation.
❌ “Annexes can be ignored” — once referenced by contract they are mandatory, especially Annex 7 (pipe) which is frequently referenced directly in pipeline work.
❌ “More spots means a looser judgment” — the acceptance rule does not change; adding spots only makes the assessment reflect the actual distribution more strictly.