Evaluation of Thermal Spray Aluminum Coating Implementation Based on Procedure Qualification Test (PQT) Inspection Data for Offshore Steel Structures

Sep 18, 2026

Thermal Spray Aluminum (TSA) coatings are used widely to protect offshore carbon steel against severe marine corrosion driven by salt, humidity, and cyclic wet–dry exposure. In practical projects, conformity is mainly verified through Procedure Qualification Tests (PQT) inspections rather than additional laboratory work. This study evaluates TSA coating implementation using documented PQT inspection records from an offshore steel structure, applying an inspection-based statistical interpretation of dry film thickness at five points. Results show thickness values from 216–357 µm (avg 284.8 µm), uniform build-up, and stable arc-sprayed characteristics, supporting PQT data as a reliable assessment basis.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages3

Reading Time8 min

AccessFree to download

Abstract

Introduction

Methodology

Thermal Spray Aluminum Application Process

Inspection-Based Evaluation and PQT Data

Evaluation of Thermal Spray Aluminum Coating Implementation Based on Procedure Qualification Test (PQT) Inspection Data for Offshore Steel Structures Fitriani,a,*, Fardin Hasibuan,b and Dwi Cahyadi Putra,c a,b)Program Studi Teknik Mesin, Fakultas Teknik, Universitas Riau Kepulauan, Indonesia c)TSA, PT. Vinnex Coatindo, Indonesia *Corresponding author: [fitri0606@gmail.com](fitri0606@gmail.com) Paper History Received: December 22th 2025 Received in revised form: March 23th 2026 Accepted: April 21th 2026 ABSTRACT Thermal Spray Aluminum (TSA) coating is widely applied for corrosion protection of offshore steel structures operating in aggressive marine environments. In practical offshore projects, the quality of TSA coating implementation is primarily verified through inspection activities conducted during Procedure Qualification Tests (PQT) . In this study, an inspection-based evaluation of TSA coating implementation was performed using documented PQT inspection records obtained from an offshore steel structure, without additional laboratory testing. TSA coating was applied using a twin wire electric arc spray process, and coating quality was assessed based on dry film thickness (DFT) measurements recorded at five inspection points. The measured DFT values ranged from 216 µm to 357 µm, with an average thickness of 284.8 µm. To ensure general applicability, the thickness distribution was interpreted using inspection-derived statistical indicators, including a thickness uniformity index and coefficient of variation. The results indicate a uniform coating build-up and stable application characteristics typical of arc-sprayed aluminum coatings. It is concluded that PQT inspection data provide a practical and reliable basis for evaluating TSA coating implementation and thickness consistency in offshore steel structure applications. KEY WORDS: Thermal Spray Aluminum, Procedure Qualification Test (PQT), Arc Spray Coating, Coating Thickness Distribution, Inspection-Based Evaluation NOMENCLATURE TSA Thermal Spray Aluminum PQT Procedure Qualification Test DFT Dry Film Thickness (µm) tavg Average dry film thickness obtained from PQT measurements (µm) tmin Minimum measured dry film thickness (µm) tmax Maximum measured dry film thickness (µm) Ut Thickness uniformity index, defined as the ratio of minimum to average thickness (–)σ Standard deviation of dry film thickness measurements (µm) CV Coefficient of variation of thickness distribution (–)μm Micrometer 1.0 INTRODUCTION Thermal Spray Aluminium (TSA) coating is widely applied for corrosion protection of offshore steel structures operating in aggressive marine environments. Exposure to high humidity, salt-laden atmosphere, and cyclic wet–dry conditions significantly accelerates corrosion of carbon steel components[1] . TSA coatings are commonly selected for offshore applications due to their combined barrier protection and sacrificial anodic behaviour, which provide long-term corrosion resistance when properly applied and inspected in accordance with recognized thermal spray practices such as ISO 2063 and AWS C2 .23M. In practical offshore projects, the quality of TSA coating implementation is primarily verified through inspection activities conducted during fabrication and installation stages. Procedure Qualification Tests (PQT) are used to demonstrate conformity between defined coating procedures and actual field application results[2] . PQT inspection records typically document surface preparation, environmental conditions, and coating thickness measurements; however, such data are rarely analysed quantitatively in academic studies, which tend to focus on laboratory-scale investigations and material characterisation (Pawlowski, The Science and Engineering of Thermal Spray Coatings) . This study addresses this gap by presenting an inspection-based evaluation of TSA coating implementation using documented PQT inspection data, with emphasis

FAQs

What is the purpose of the study on TSA coating implementation?

To evaluate the implementation quality of Thermal Spray Aluminum coatings using inspection data from Procedure Qualification Tests (PQT) for offshore steel structures.

How was coating quality assessed in the study?

Through dry film thickness (DFT) measurements recorded at five inspection points during PQT, followed by quantitative statistical interpretation of thickness distribution and uniformity.

What were the main findings regarding DFT results and coating behavior?

Measured DFT values ranged from 216 µm to 357 µm with an average of 284.8 µm, indicating uniform coating build-up and stable application characteristics typical of arc-sprayed aluminum.

Sep 18, 2026

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