S O L U T I O N S .





Non-Destructive Testing (NDT) plays a crucial role in various industries, including construction, manufacturing, and oil and gas, where ensuring the integrity of materials and structures is paramount. One important aspect of NDT is holiday testing, which is used to detect and locate discontinuities, such as pinholes or voids, in protective coatings and linings. This article explores the significance of holiday testing in the NDT industry and highlights the exceptional services provided by NDT and PWHT Solutions, a leading company in this field.

Understanding Holiday Testing:

Holiday testing, also known as spark testing or porosity testing, is a method used to identify discontinuities in coatings, such as pipelines, tanks, or concrete structures. These discontinuities, commonly referred to as “holidays,” can lead to corrosion, leakage, and decreased durability if left undetected. By performing holiday testing, NDT technicians can identify and repair these flaws before they compromise the structural integrity of the material or asset.

Holiday Testing Process:

The holiday testing process involves the following steps:

Equipment Setup: The NDT technician selects the appropriate equipment, which typically consists of a low-voltage direct current (DC) holiday detector, a grounding brush, and a probe electrode. The equipment is calibrated and adjusted to ensure accurate results.

Surface Preparation: The surface to be tested is thoroughly cleaned and prepared to remove any contaminants or loose materials that could interfere with the testing process. This step ensures optimal contact between the electrode and the coating.

Test Procedure: The NDT technician systematically moves the electrode across the surface of the coating, maintaining a consistent distance and speed. The electrode emits a low-voltage DC current that passes through the coating. If a holiday or discontinuity exists, the current will flow through the coating and generate a spark or audible alarm.

Holiday Detection: The technician identifies the location and size of the holiday by observing and recording the sparks or alarms generated during the test. Further evaluation may be conducted to determine the severity and extent of the discontinuity.


NDT and PWHT Solutions: Delivering Excellence in Holiday Testing Services:

Among the reputable companies in the NDT industry, NDT and PWHT Solutions stands out for its commitment to quality, safety, and customer satisfaction. They offer a wide range of services, including holiday testing, that are tailored to meet the unique requirements of each client. Here’s how NDT and PWHT Solutions delivers the best holiday testing services:

Expertise and Experience: NDT and PWHT Solutions boasts a team of highly skilled NDT technicians with extensive experience in holiday testing. They possess in-depth knowledge of various coating systems and are proficient in the operation of advanced holiday testing equipment.

State-of-the-Art Technology: The company utilizes cutting-edge equipment and techniques to ensure accurate and reliable holiday testing results. Their equipment is regularly calibrated and maintained to meet industry standards, ensuring precise detection of even the smallest discontinuities.

Comprehensive Reporting: NDT and PWHT Solutions provides detailed reports, including photographs and documentation of detected holidays. These reports enable clients to understand the nature and extent of any coating issues, facilitating prompt repairs and maintenance.

Compliance and Safety: The company adheres to industry regulations and safety standards, prioritizing the well-being of their technicians, clients, and the environment. They employ rigorous safety protocols during the testing process and strictly follow industry guidelines and codes.

Tailored Solutions: NDT and PWHT Solutions recognizes that each project is unique, and they work closely with clients to develop customized holiday testing strategies. They consider factors such as project specifications, coating materials, and environmental conditions to deliver optimal testing solutions.



Holiday testing plays a critical role in maintaining the integrity of protective coatings and linings in various industries. By partnering with a trusted company like NDT and PWHT Solutions, organizations can ensure the highest standards of quality and safety in their assets. With their expertise, advanced technology, and commitment to customer satisfaction, NDT and PWHT Solutions continues to be a leader in delivering exceptional holiday testing services in the NDT industry.

Holiday testing, also known as spark testing or pinhole testing, is a non-destructive testing (NDT) method used to detect discontinuities or defects in insulating coatings applied to conductive substrates. While holiday testing is not specific to the NDT industry alone, it is commonly employed in industries such as oil and gas, construction, and manufacturing, where protective coatings are applied to prevent corrosion and maintain structural integrity. The benefits of holiday testing in the NDT industry include:

Detecting coating defects: Holiday testing helps identify pinholes, cracks, or thin spots in protective coatings. By detecting such defects early on, it ensures the integrity of the coating and prevents the underlying substrate from being exposed to corrosion or other forms of degradation.

Ensuring corrosion protection: Protective coatings act as a barrier between the substrate and the surrounding environment, protecting the material from corrosion. Holiday testing ensures that the coating is continuous and free from any discontinuities that could allow corrosive agents to penetrate and damage the substrate.

Compliance with standards and specifications: Many industries have specific standards and specifications for coating thickness and quality. Holiday testing allows for compliance with these standards, ensuring that coatings meet the required thickness and exhibit the necessary integrity.

Preventing premature coating failure: Coating failure can lead to significant maintenance costs, repairs, and even safety risks. By identifying defects through holiday testing, necessary repairs or reapplication of the coating can be carried out before significant damage occurs, thus preventing premature failure.

Cost-effective inspection: Holiday testing is a relatively simple and cost-effective method compared to other NDT techniques. It is relatively quick to perform and requires minimal training for operators. This makes it an attractive option for inspecting large surface areas or projects with tight time and budget constraints.

Improved asset lifespan: The detection and repair of coating defects through holiday testing contribute to the longevity of assets and infrastructure. By ensuring the integrity of protective coatings, the service life of structures can be extended, reducing the need for frequent maintenance, replacement, or repairs.

Enhanced safety: Coatings applied to structures, pipelines, or vessels often serve as a safety measure, protecting against chemical or environmental hazards. Holiday testing helps ensure the efficacy of these coatings, reducing the risk of accidents, leaks, or environmental contamination.

Quality control and assurance: Holiday testing provides a means for quality control during the coating application process. It helps identify and address coating defects before the project is completed, ensuring that the final product meets the required quality standards.

Overall, holiday testing in the NDT industry offers numerous benefits, including improved corrosion protection, compliance with standards, cost-effectiveness, extended asset lifespan, enhanced safety, and quality control. By incorporating holiday testing into inspection protocols, industries can maintain the integrity of protective coatings and safeguard their assets, leading to long-term cost savings and operational efficiency.

detect unacceptable discontinuities (voids, pinholes, fisheyes, cratering, and sometimes weaknesses) in a non-conductive coating film which are not easily visible.