Protecting Steelwork from Hydrocarbon Fuel Fires

A New Certification Category for the Protection of Steelwork Exposed to Fires Burning Hydrocarbon Fuels is Now Available from UL.

Over the past two decades, the ANSI/UL 1709 (Rapid Rise Fire Tests of Protection Materials for Structural Steel) test standard has grown in importance across the worldwide petrochemical industry for the hydrocarbon fire protection of structural steel. The standard is currently considered the ‘default’ standard in many parts of the world, particularly those which actively use guidance for the petrochemical industry published by the American Petroleum Institute (API).

However, legislation and guidance in many parts of the world impose additional requirements on the products that the current UL 1709 test method cannot fully encompass. In order to ensure that UL certification remains relevant to the needs of the industry, UL has undertaken a review of the industry needs and developed a new certification category that includes a wider suite of characteristics for steelwork protection when used in petrochemical type installations. These characteristics will be collated into a certification program as a new UL service provision.

Mandatory Characteristics
The UL program for the protection of steelwork exposed to fires burning hydrocarbon fuels – such as those found in petrochemical installations – will be based upon the product complying with UL 1709 as a mandatory minimum.

Fire Exposure
As might be expected for evaluation of products in installations such those processing hydrocarbon fuels, the test method uses a higher heat and energy than a fire condition based on a ‘standard’ building fire, which uses a cellulosic fuel source as reflected in ANSI/UL 263 (ASTM E119) (Fire Tests of Building Construction and Materials). Therefore the new certification category will be based upon a mandatory requirement of satisfying UL 1709 as a minimum.

ANSI/UL 1709 has grown in importance in the petrochemical industry for the hydrocarbon fire protection of structural steel. It is currently considered the ‘default’ standard around the world.

UL 1709 was developed specifically to evaluate products subjected to hydrocarbon fires and is widely accepted as the means of evaluating steelwork protection in many regions internationally. For this reason, and without wanting to add a new requirement, UL 1709 will form the basis of UL’s new Hydrocarbon Category.

Environmental Exposure
Petrochemical type installations are obviously built to exploit the presence of underground natural resources and/or to provide a strategically located onward transport facility for the refined products. Additionally the industrial nature of the facilities can result in a corrosive atmosphere for the building infrastructure.

This can, and often does, mean that the facilities are placed in more challenging natural environments such as those that suffer extreme heat and cold or at the edge of oceans that, literally by their very nature, means the products used for the buildings need to be stable when exposed to these environmental factors. This is particularly important if the products are to provide a life safety function such as fire protective materials.

The new Hydrocarbon Category will therefore also include evaluation of the protective coating against the long-term effects of environmental exposure, often a critical factor in the performance of materials in petrochemical installations.

The method is already a mandatory part of UL 1709 and will also be a requirement of UL’s new Hydrocarbon Category. In time, these environmental requirements will transition to include a requirement to comply with the development of UL 2431 (Durability of Spray-Applied Fire Resistive Materials).

Optional, Additional Characteristics
In addition to the requirement for UL 1709, the scheme will allow for optional characteristics to be included within the product’s claim of performance. These characteristics are aspects of protection that are often required of the product when installed in installations such as petrochemical facilities. Mandatory and optional characteristics, which have been complied with, will all be included within the scope of the certification.

Jet Fire
Due to the pressurised nature of the hydrocarbon fuels within the pipes and vessels within the facility, fires can be of a very fierce nature, even above the temperatures and ferocity of those specified in UL 1709. For this reason an International Standard, ISO 22899 (Determination of the resistance to jet fires of passive fire protection materials – Part 1: General requirements – First Edition) has been developed to evaluate protective materials against the temperature and erosive nature of fire emanating from pressurised hydrocarbon-carrying pipes and vessels. These fires, colloquially known as ‘jet-fires’, have become increasingly specified in the petrochemical industry and, after discussion with stakeholders, UL believes there is much value in including this optional characteristic within this certification category.

UL 1709 was developed specifically to evaluate products subjected to hydrocarbon fires. It is widely accepted as the means of evaluating steelwork protection in many regions internationally.

Multi-Temperature Analysis
The hydrocarbon certification category also includes product design tables for alternate critical core design temperatures. This is achieved by conducting an evaluation of the test data called the Multi-Temperature Analysis (MTA).

The purpose of this analysis is to identify the thickness of coating material necessary to keep a specific substrate below a specific temperature for a specific duration. This philosophy is in line with the philosophy and criteria of UL 263 and UL 1709, but does not restrict the limiting steel temperatures to 593°C/704°C and 538°C/649°C for beams and columns respectively.

The information relating to multi-temperatures is often used in performance-based fire protection applications where a specific fire protection solution will require a specific level of fire protection due to the different heat exposure generated from the anticipated fuel source. In order to accommodate this, alternate critical core temperature designs for the products have been developed at various temperatures ranging from 371°C to 760°C in increments of 38°C. The ability to have the data analysed using the MTA method will be included as an option within the category.

Fire Exposure
Products certified under this certification may also be exposed to additional fire exposure conditions. The standards for such elective fire exposures will included BS 476: Part 20: Annex D.

In some specifications, often for separating bulkheads and decks, the test method referenced in Annex D of BS 476 (Fire Tests on Building Materials and Structures – Part 20: Method for Determination of the Fire Resistance of Elements of Construction) is specified as the temperature exposure. Therefore the new certification category will allow for testing to this standard and on these types of constructions as an optional additional characteristic.

Environmental Durability
In addition to the mandatory minimum environmental evaluation that is included as part of the UL 1709 evaluation, the scheme will allow for additional evaluation via Norsok M-501 (Surface preparation and protective coating) Revision 5 test method. This evaluation method is increasingly used in the petrochemical industry to evaluate the protective properties of materials and UL has, accordingly, included this testing as an optional characteristic.

Final Certification
The end result will be a certification coverage that will address the mandatory minimum of UL 1709 and environmental exposure, but can also include other characteristics that the product may have been tested and evaluated against. The resulting scope of certification will be ‘listed’ on UL’s Online Certifications Database viewable publically via www.ul.com

This will enable the products that have certification against this category to be compared side-by-side and their scope of performance to be judged on an even basis. Certification to this category will also provide the end user with reassurance that the performances shown in the certification are evaluated independently by UL, a reputable third- party certification body, indicating that the product is made under regularly inspected factory production controls leading to a consistently manufactured product.

For further information, go to http://industries.ul.com/building-materials/fire-resistive-products/