SSPC-PA 2 Coating Thickness - Protective Coatings Paint Application Standard

The standard "SSPC-PA 2 Coating Thickness - Protective Coatings Paint Application," developed by the Society for Protective Coatings (SSPC), specifies requirements for measuring instrument calibration, measuring instrument verification and adjustment procedures, the number of measurements to be obtained, and measurement tolerances. However, this standard is generally considered a standard for determining how to measure paint thickness.

Essentially, the process of measuring coating thickness consists of the following basic steps:

• Step one: Device calibration
• Step two: Verification of the measuring device on certified coated standards or certified shims
• Step three: Base metal reading acquisition or meter adjustment (using certified or measured shims)
• Step four: Measure the coating thickness
• Step five: Correct base metal reading (if obtained)

The SSPC-PA 2 standard addresses two types of dry film thickness measuring devices, both supplied by various companies:

• Magnetic pull gauges are classified as Type 1. While their use has declined, these gauges are still readily available and are still used by some. These gauges place a permanent magnet directly in contact with the coated surface. The force required to pull the magnet away from the surface is measured and converted to the coating thickness, which is displayed on a scale on the gauge. The operating principle is quite simple. Less force is required to remove a magnet from a thick coating, while more force is required to remove it from a thinner coating. The scale is not linear.
• Electronic meters are classified as Type 2. These meters use electronic circuitry to convert a reference signal into coating thickness and are more popular than Type 1 meters. They are generally considered faster, more accurate, and easier to use.

ASTM D7091 specifies three operational steps that must be performed before coating thickness measurement to ensure reliability: gage calibration, gage verification, and gage adjustment. These steps are incorporated by reference into the SSPC-PA 2 standard and are completed before coating thickness measurements are taken to determine compliance with a specific coating thickness range.

Verification of the meter is usually performed using certified coating thickness standards (for Type 1 or Type 2 meters) or certified shims (for Type 2 meters).

In short, the SSPC-PA 2 standard specifies procedures for measuring the dry film thickness of a non-magnetic coating applied to a magnetic substrate using commercially available magnetic measuring instruments. These procedures are intended to supplement, and are not intended to replace, manufacturers' instructions for manual instrument operation. This standard describes calibration and measurement procedures for two types of measuring instruments: tensile measuring instruments (Type 1) and fixed-pressure probe measuring instruments (Type 2). This standard defines a procedure for determining whether the film thickness over an extended area complies with specified minimum and maximum levels.

The type of gauge is determined by the specific magnetic properties used to measure thickness, not by the data readout method (digital or analog). This standard does not cover gauges that measure the effects of eddy currents in the substrate.

The SSPC-PA 2 standard includes:

• Calibration, verification and measurement procedures.
• The number of measurements required to comply with a thickness specification.
• Notes on gauge principles and various factors affecting thickness measurement.
• A numerical example of thickness measurement over an extended area.
• A numerical example of verifying the calibration of Type 2 measuring instruments using plastic wedges.

This standard is particularly important because it provides a systematic, consistent, and accurate method for verifying the dry film thickness of protective coatings applied to steel surfaces in industrial and infrastructure environments. It is also considered important for the following reasons:

• Ensures coating performance and durability: The effectiveness of protective coatings (such as anti-corrosion paints) depends largely on the application of the correct film thickness. Too thin will provide inadequate protection, while too thick will crack or delaminate.
• Increases audit consistency: Provides clear guidance on how many measurements to take, where to take them, and how to average them. Reduces subjectivity and inconsistencies between auditors or projects.
• Supports quality control and contract compliance: Often required in specifications for bridges, pipelines, ships, and structural steel. Prevents disputes and rework by ensuring contractors meet thickness requirements.
• Integrates with modern inspection tools: This standard applies to both Type 1 (mechanical) and Type 2 (electronic) magnetic measuring instruments. It guides inspectors on correct instrument calibration and use.
• Referenced by other standards: This standard is frequently cited in standards such as the SSPC-SP surface preparation series, NACE and ISO coating inspection standards.

Typical industries using the SSPC-PA 2 standard include:

• oil and gas
• Shipbuilding
• Infrastructure (bridges, tanks, pipelines)
• Industrial maintenance
• Military and marine coatings

As a result, the SSPC-PA 2 standard is crucial for verifying that protective coatings are applied correctly and perform as intended, especially in harsh or regulated environments.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the "SSPC-PA 2 Coating Thickness - Protective Coatings Paint Application" standard.