A hydrostatic test is a critical procedure used to verify the structural integrity of pressure vessels such as pipelines, heat exchangers, storage tanks, and ship voids. While this testing method is essential for safety and compliance, it introduces a significant risk: corrosion.
When left unprotected, the presence of water and ionic contaminants during a hydrostatic test can rapidly corrode metal surfaces, jeopardizing long-term system performance. That’s why ZERUST® Hydrostatic Test Additives are engineered to deliver unparalleled corrosion protection during and after testing.
Protect Your Equipment During Hydrostatic Testing
Hydrostatic testing can expose pipelines, pressure vessels, and tanks to corrosion risks caused by water, oxygen, and ionic contaminants. Discover how ZERUST® hydrostatic testing corrosion protection solutions help prevent rust, neutralize contaminants, and safeguard system integrity during and after testing.
During a hydrostatic test, water is pressurized inside a vessel to detect leaks and ensure mechanical reliability. However, untreated water contains dissolved ions, oxygen, and minerals that can lead to:
Rust formation on ferrous metals
Pitting and scale buildup
Long-term internal corrosion
Environmental discharge concerns
ZERUST® has developed a suite of hydrostatic test fluid additives that counteract these threats with safe, globally compliant, and high-performing formulations tailored to different metal types and testing environments.
ZERUST® Hydrostatic Test Additives: Product Overview
For ferrous metals | Anti-rust + Hard water scale prevention
ZERUST®/EXCOR® Axxatec™ HST-20L is a powerful water treatment concentrate formulated to deactivate ionic contaminants that cause rust and scale during hydrostatic testing. Ideal for pressure vessels composed of ferrous metals, this additive ensures temporary corrosion protection during and post-test.
Key Features:
Deactivates ionic contaminants to prevent rust and deposits
Not compatible with aluminum, zinc, galvanized, or yellow metals
Non-flammable and solvent-free
Compliant with TSCA, RoHS, and REACH
Environmentally safe; can be reused or discharged per regulations
Ideal for: pipelines, steel tanks, ship voids, and heat exchangers made of ferrous metals
Ideal for: pipelines, tanks, and vessel systems made of ferrous metals where hard water is used or where a dry, powder format is preferred.
Tip: For systems that contain aluminum or yellow metals, use Axxatec™ HST-20L in conjunction with Axxatec™ HST-M100.
Learn More About Axxatec™ HST-20L
Axxatec™ HST-20L neutralizes ionic contaminants that cause rust and scale during hydrostatic testing. This water treatment concentrate helps protect ferrous metal systems such as pipelines, tanks, and pressure vessels while supporting safe and efficient testing operations.
For multimetal systems | Broad-spectrum protection
When your hydrostatic test involves aluminum, copper, brass, or a mix of metal alloys, Axxatec™ HST-M100 is the ideal additive. As a result, this water-soluble solution provides corrosion protection for a wide range of metals and continues to inhibit corrosion after the test is complete.
Key Features:
Compatible with aluminum, copper, brass, and ferrous metals
Tip: When testing only ferrous metal systems, pair with AxxaVis™ HST-10 for enhanced cost-efficiency.
Discover Axxatec™ HST-M100 for Multimetal Systems
Axxatec™ HST-M100 protects multimetal systems during hydrostatic testing, including aluminum, copper, brass, and ferrous metals. This water-soluble additive helps prevent corrosion while supporting safe, efficient testing operations and easy system flushing after the test is complete.
For ferrous metals | Powder-based corrosion inhibitor
AxxaVis™ HST-10 is a water-soluble powder additive that transforms hard water into a corrosion-safe testing medium for ferrous metal vessels. It’s an excellent option for industrial operations that rely on hard or variable water sources.
Key Features:
Deactivates ionic contaminants to prevent rust and scale
Designed for ferrous metals only
Powder format allows for convenient mixing and storage
Compliant with global environmental and safety standards
Non-hazardous, non-flammable, and solvent-free
Ideal for: facilities using hard water or requiring a powdered additive format
Tip: For systems involving yellow/red metals, use AxxaVis™ HST-10 alongside Axxatec™ HST-M100 for full-spectrum protection.
Learn More About AxxaVis™ HST-10
AxxaVis™ HST-10 converts hard water into a corrosion-safe medium for hydrostatic testing of ferrous metal systems. It helps deactivate ionic contaminants that cause rust and scale, providing reliable protection for pipelines, tanks, and pressure vessels during testing.
All ZERUST® hydrostatic test additives are formulated with environmental stewardship in mind. These products:
Meet global compliance standards (TSCA, RoHS, REACH, ECHA SVHC)
Are safe for discharge in most regulated environments
Reduce operational costs through reusability in select applications
Offer non-flammable, solvent-free safety for operators and equipment
Choosing the Right Additive for Your Hydrostatic Test
Metal Type
Recommended Product
Ferrous metals only
AxxaVis™ HST-10 or Axxatec™ HST-20L
Multimetals (aluminum, brass, copper)
Axxatec™ HST-M100
Ferrous + yellow/red metals
Axxatec™ HST-20L + HST-M100 combo
Need help selecting the best product? Contact ZERUST® to speak with a corrosion specialist.
Learn More About Hydrostatic Testing and Corrosion Protection
Want to better understand hydrostatic testing procedures and the role corrosion inhibitors play in protecting equipment? Explore our comprehensive guide covering the hydrostatic testing process, advantages, and effective corrosion protection strategies for pipelines, pressure vessels, and industrial systems.
A hydrostatic test validates pressure performance, but only ZERUST® ensures that your system remains protected after the test ends. Whether you’re protecting miles of pipeline or specialized ship voids, ZERUST’s suite of hydrostatic test additives offers:
Superior corrosion protection
Ease of use
Global compliance
Eco-conscious performance
Don’t Let Corrosion Undermine Your Results
Get in touch with ZERUST®/EXCOR® today to learn more about how our hydrostatic test additives can protect your investment and streamline your testing protocols.
Need Help Choosing the Right Hydrostatic Test Additive?
Selecting the right corrosion inhibitor for application depends on metal composition, water quality, and system conditions. ZERUST® corrosion experts can help you choose the most effective additive to protect pipelines, pressure vessels, tanks, and other critical equipment during testing.
Tom White is the Marketing Manager at ZERUST®, bringing almost a decade of expertise in Vapor Corrosion Inhibitor (VCI) technologies and corrosion prevention solutions. He leads strategic marketing initiatives that showcase ZERUST®’s global product portfolio, from sustainable VCI packaging films to advanced rust preventatives and cleaners. Tom is deeply involved in product launches, trade show planning, digital marketing, and customer engagement, ensuring that ZERUST®’s innovative solutions reach the right industries and decision-makers. With a strong focus on aligning technical expertise with customer needs, he helps drive the brand’s growth and strengthen its position as a leader in corrosion protection worldwide.
AxxaVis™ HST-10 powder additive is an effective hydrostatic testing corrosion inhibitor that treats water used to test pressure vessels and voids. It reduces hardness and deactivates ionic contaminants like chlorides found in municipal water sources, preventing rust and hard water deposits on metals.
Axxatec™ HST-20L is a highly effective water treatment concentrate designed to deactivate ionic contaminants found in water sources that cause rust and hard water deposits on metals during hydrostatic testing.
Axxatec™ HST-M100 is a low to no-foam, water-soluble hydrotesting fluid additive designed for corrosion protection in hydrostatic testing. Ideal for use with aluminum, copper, brass, and ferrous metals.
To provide the best experiences, we use technologies like cookies to store and/or access device information. Consenting to these technologies will allow us to process data such as browsing behavior or unique IDs on this site. Not consenting or withdrawing consent, may adversely affect certain features and functions.
Functional
Always active
The technical storage or access is strictly necessary for the legitimate purpose of enabling the use of a specific service explicitly requested by the subscriber or user, or for the sole purpose of carrying out the transmission of a communication over an electronic communications network.
Preferences
The technical storage or access is necessary for the legitimate purpose of storing preferences that are not requested by the subscriber or user.
Statistics
The technical storage or access that is used exclusively for statistical purposes.The technical storage or access that is used exclusively for anonymous statistical purposes. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you.
Marketing
The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes.
To provide the best experiences, we use technologies like cookies to store and/or access device information. Consenting to these technologies will allow us to process data such as browsing behavior or unique IDs on this site. Not consenting or withdrawing consent, may adversely affect certain features and functions.
Functional
Always active
The technical storage or access is strictly necessary for the legitimate purpose of enabling the use of a specific service explicitly requested by the subscriber or user, or for the sole purpose of carrying out the transmission of a communication over an electronic communications network.
Preferences
The technical storage or access is necessary for the legitimate purpose of storing preferences that are not requested by the subscriber or user.
Statistics
The technical storage or access that is used exclusively for statistical purposes.The technical storage or access that is used exclusively for anonymous statistical purposes. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you.
Marketing
The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes.
A hydrostatic test is a critical procedure used to verify the structural integrity of pressure vessels such as 
1. 
2. 
3. 
