Unrivaled Solution for Fire Protection of Load-Bearing Structures in Harsh Environments

In the late 1970s the development of oil&gas industry brought up a challenge of choosing fireproof materials for supporting steel structures, for hydrocarbon fire scenarios.

First, the problem is linked to explosion and temperature spike inherent to hydrocarbon fire event; often, this neutralizes the active fire suppression systems and destructs fireproof materials. Second, in developing new remote Arctic oil&gas fields (including offshore), the choice of fire-resistant materials must consider such extras as freezing temperatures down to -60°C, excessive moisture, temperature extremes and wind loads.

The question is, which fire protection to use

To address this complex issue, global industry successfully uses developed in early 80s intumescent fire-proof coating (passive fire protection) based on epoxy resins. Passive fire protection prevents heating of steel structures to the critical temperature, for a set period of time. In case hydrocarbon fire, the coating swells to several times the size (5-6 times), forming a dense heat-resistant layer of ash, which slows down the heating of the metal to the critical temperature at which steel loses its structural strength (usually this means a temperature above 500°C).

The use of flame retardants delays heating of the structure up to 300 minutes, which often gives time to save the integrity of the supporting structures until fire localization and elimination (for comparison, without the coating, 1.7 m high I-beam No. 20 heats to 500°C in 4-8 minutes). The thickness of the flame retardant coating is 5 to 22 mm, depending on the structure’s section factor and the required fire resistance class. Here, it is crucial to understand that any through damage to the coating - chipping, cracking, peeling due to mechanical stress, structural vibrations (particularly strong in sub-zero temperatures) - lead to more rapid heat on load-bearing structures, violating their integrity. (Fig. 1)

PPG has developed an unbeatable global solution - a flexible coating PittChar XP® for fire protection of the structures under all atmospheric conditions anywhere on Earth, including in Arctic conditions and offshore projects. The uniqueness of the coating is that it maintains a highly elastic state (flexibility) in a wide temperature range - from deep freezing temperatures and up to just before the swelling process. At -40°C, relative elongation of the coating is 5% (for reference - at 20°C relative elongation is 19.4%). This property means that the coating weakens the internal stresses arising from temperature spikes, vibrations of metal structures and mechanical effects, as described below (Fig. 2).

Temperature spikes

The coating withstands 25 cycles of rapid heating/cooling between -180°C to +43°C for 3 minutes (one cycle) without cracking or peeling of the metal (or soil) surface. We also confirmed that metal structure with PittChar XP ® retained its fire-retardant properties after being kept in liquid nitrogen at -190.5°C and subsequent burning in the furnace. Over the past 20 years the coating has been applied and is successfully used in Arctic conditions in Norway, on offshore oil platforms of Stat Oil, Philips Petroleum, Norsk Hydro, Shell, Dolphin, Total, Amoco.

Vibrations of metal structures

Metal vibrations occur during equipment operation, wind effects, or structure installation. The main impact of vibrations, which is only exacerbated by sub-zero temperatures, falls on adhesion bonds between soil and metal, as well as between the ground and flame-retardant coating. Solidification of the fire retardant coating may result in excessive stress on contact with the ground, which weakens the adhesive bonds between the soil and the metal and, in case of strong vibrations could lead to invisible from outside peeling of the coating from metal. Though having years of experience, we have never encountered such problem when using PittChar XP®.

Mechanical stress

Transportation and installation of metal structures with PittChar XP® results in minimal possible chips and damage compared to competitive products, and these can easily be repaired later. Since the PittChar XP®   coating is flexible in a wide range of temperatures, leading to damage mechanical stresses are often minor and in these cases the repair painting is not required.

The PittChar XP® coating, while being flexible in a wide temperature range, also achieves the ultimate goal - retaining for decades the integrity of the coating and load-bearing structures regardless of combined impact of extreme weather conditions, chemicals, vibration and mechanical stress when installing and operating the structures. This ensures maximum efficiency of the coating in the event of a hydrocarbon fire. (Fig. 3)

For over 30 years PittChar XP® coating has been successfully used in oil&gas production, transportation and processing projects. Special demand exists for oil platforms operated in marine and deep-freezing atmospheric conditions. (Fig. 4)

The PittChar XP® coating by PPG is unbeatable flexible fire-retardant solution for load-bearing structures in harsh cryogenic environments.