In response, 2015 saw the debut of the UL 1709 Edition 5. The highlight of this edition introduces the UL2431 durability test, formulated to test the resistance of coatings against temperature-induced stress cracks. The test employs a stringent wet/freeze/dry cycle. A cycle consists of the equivalent of rainfall at the rate of 18mm/hour (0.7 inches/hour) of water for 72 hours, followed by a temperature of -40 ±2.8° C (-40 ±2.8°F) for 24 hours, and then a dry atmosphere of +60 ±2.8°C (+140 ±5°F) for 72 hours to simulate real-world conditions. This cycle will be repeated 12 times before the specimen is fire-tested and compared to a control specimen.
By integrating the UL Environmental Standard 2431 test into UL 1709 Edition 5, the standard gauges the fire resistance of materials and ensures that they can withstand the severe environmental conditions and extreme hydrocarbon hazards.
UL 1709 Edition 5: Raising the bar in fire protection testing
UL 1709 Edition 5 has plenty of similarities to Edition 4. Still, it's the addition of a few aggressive tests and new standards that manufacturers must put their products through that make it a better barometer of fire protection performance. Similar to UL 1709 Edition 4, UL2431 includes the following tests of individual samples:
- Aging test
- High humidity test
- UV test with a 135-day exposure
- Salt spray test
- Wet freeze dry cycle
- Industrial atmosphere exposure
- Optional acid and solvent spray
After subjecting individual samples to these test environments, they were evaluated under the UL 1709 fire test. To achieve the UL 1709 Edition 4 certification, a sample exposed to the above conditions had to perform within a 25% deviation range from an unexposed control sample.
As part of UL2431, UL 1709 Edition 5 includes the same tests, in addition to new durability tests, including:
Combined high humidity and UV Tests: Merging these tests challenge the material with an eight-hour cycle of UV at +70°C (+158°F), followed by four-hour condensation at 50°C (122°F), running for 5,000 hours. This combined test intensifies the strain on tested materials.
Enhanced Wet-Freeze-Dry Cycle Test: Introducing a challenging 12-cycle repetition that subjects the product to 72 hours of rain, 24 hours of freezing temperatures, and 72 hours in dry, hot conditions. This process simulates the rapid environmental changes materials face in many real-world settings.
Salt Spray Testing: This 90-day (2,160-hour) test, following ASTM B117 salt spray, evaluates corrosion resistance under prolonged saline conditions.
Air Erosion Test: To assess a material's resilience against persistent high winds, an ASTM E859 method is employed where materials face wind speeds up to 96.6 km/hour (60 mph).
Impact Resistance Test: This test drops a two-inch steel ball from 20 feet through a three-inch diameter pipe, which may be more challenging for cementitious-based products.
Vibration Test: Reflecting the vibrations structures endure, this test evaluates the coating's resistance to frequencies between 10-60 Hz. The sample is subjected to a five-minute exposure each at a two Hz increment, plus a two-hour exposure at the maximum resonance or 60 Hz should no resonance be observed during the variable frequency test.
Enhanced Performance Requirements: The permissible deviation from an unexposed sample's fire performance is now tightened from 25% to 15%.
Test regimens and results
Before the launch of UL 1709 Edition 5, certification changes from the first to the fourth edition were marginal. This often meant a product certified under Edition 1 could still be applicable under Edition 4. However, by July 2022, this leniency ceased. For a UL 1709 certification, products must comply with the stringent requirements of Edition 5, which includes the rigorous UL2431 environmental standards.
The public can access the UL directory Product iQ® to verify product certifications. It offers comprehensive insights, such as the protective topcoat required for UL2431 compliance. These topcoats remain vital, so neglecting their maintenance can considerably jeopardize fire protection efficiency.
The addition of UL Environmental Standard 2431
Several contributing factors led to the addition of UL2431 as part of UL 1709 Edition 5. Hydrocarbon processing facilities, progressively situated in diverse and extreme climatic conditions, remain at the forefront of these concerns. The hazards posed by temperature extremities leading to cracks in metal substrates and PFP coatings cannot be overemphasized, as they become vulnerable points for heat ingress, elevating fire risks. Likewise, offshore facilities grapple with the challenges of high humidity, forceful winds, and even the direct impact of waves on specific structural areas.
The Köppen climate classification, which categorizes global climates into 30 distinct zones with five primary clusters - tropical, dry, temperate, continental, and polar - further underscores the complexity of these environmental conditions, thus ensuring that durability tests robustly represent these varied regions is paramount. The establishment of UL 1709 Edition 5 serves as a versatile standard, with its testing rigor emulating the challenges of these diverse climates, ensuring coatings that secure this certification offer unparalleled fire protection, even in the most severe environments.
This edition also integrates insights from the tragic September 11, 2001, World Trade Center attacks. The significant damage to the fireproofing witnessed after the initial crash necessitated the inclusion of tests focusing on air erosion, vibration, and impact. Recognizing the environmental pressures specific to various global locales—be it UV exposure, humidity fluctuations, temperature extremes, erosive elements, or seismic activities—the updated UL 1709 standard underscores the importance of resistance to these challenges.
Beyond environmental considerations, the edition delves into non-environmental factors, accentuating rigorous impact, abrasion, and chemical tests. However, it's pivotal to understand that these comprehensive tests do not encompass all facets of durability. Manufacturers should include further tests such as three or four-point bend testing, elongation, adhesion, shore hardness, and fatigue in their evaluation regimes to gauge durability.
The evolution of PFP coatings
As testing standards have evolved, so have the solutions. For instance, PPG PITT-CHAR NX epoxy intumescent coating is designed specifically to meet the dual challenges of severe fire hazards and cryogenic spills. It remains the only product to have been verified by UL to endure double exposure to the demanding UL2431 testing standards. This enhanced durability indicates that the coating went through each conditioning test and passed each after exposure not once but twice (achieved without needing a protective topcoat) to provide owners and operators of LNG, oil, gas and petrochemical facilities with a high performance PFP coating.
