Monday, December 22, 2014

Fireproofing Materials

The excellent fire protection afforded by concrete has been demonstrated time and time again over 90 years of experience in the petrochemical industry. The high mass and low thermal conductivity of concrete make it very effective at reducing heat input to the underlying structure. Poured-in-place concrete, using forms, is common for columns and beams. Gunite is pneumatically applied to spheres and other structures where the use of forms for poured-in-place concrete is impractical. The principal drawback with gunite application is that it can be very messy.

Post-fire inspections have shown that concrete spalls to various degrees but the general conclusion is that concrete/gunite performs satisfactorily with the steel structures well protected. Wire reinforcement is commonly used. Reinforcement does not prevent cracking and spalling of the concrete but it does minimize the loss of fractured material during a fire exposure.
Excellent Fire Endurance of 30 Year Old Concrete
A refinery fire initiated at a gas oil line from a crude distillation unit and burned for about 12 hours. The main pipe rack near the crude tower at the center of the fire was damaged beyond repair. The support structure for the crude tower overhead equipment was severely damaged.

The aluminum jacketed thermal insulation on vessels and exchangers was destroyed (aluminum melts at about 660°C) but most pressure vessels and heat exchangers, showed no visible signs of permanent damage, primarily due to the cooling effect of liquid contents. Gaskets that had been damaged and high strength bolts that had been tempered by the fire exposure, had to be replaced.

Thermal expansion and contraction on structural support columns near ground zero caused a good deal of cracking and de-lamination of the concrete fireproofing; however, no evidence of deep damage to the concrete was found. The main concern was for the support structure of the crude distillation tower as the refinery is located in a seismic zone.
The radiant heat and direct fire exposure caused spalling of the 30 year old concrete cover on the exterior of the vessel skirt. Firewater cooling added to the spalling problem. Some rebar was exposed at the crude tower foundation, most notably on the side of the tower that faced the fire. Concrete was removed for inspection of the crude tower skirt and anchor bolts. No heat buckling of the skirt or distortion of the bolt seatings was observed. Bolts were checked for cracks and hardness measurements were made to confirm strength. The concrete fireproofing had prevented any permanent damage to the vessel skirt and anchor bolts. The 30 year old concrete was now a mess but it had served its function.


Wednesday, December 17, 2014

Why Fireproofing is used?

Why Fireproofing is used?

Typically, fireproofing is designed to protect the structural steel which supports high risk or
valuable equipment. The failure point is generally considered to be 1000°F, as this is the point where steel has lost approximately 50% of its structural strength. The aim then, is to prevent structural steel from reaching 1000°F for some period of time. Tanks, pressure vessels, and heat exchangers may experience a significant cooling effect from liquid contents and so, less fireproofing protection is generally required. Some thermal insulation systems may serve a dual role as fireproofing and this is common with some pressure vessels. Piping may be insulated but it is not generally considered to be fire proofed.

Fireproofing needs to be durable to survive the rigors of every day life in the plant so that if and when a fire does occur, the fire endurance properties have been maintained and the fireproofing can be depended on to function satisfactorily. Everyday exposure may involve mechanical abuse, exposure to oil, solvents, and chemicals, and outdoor weathering for prolonged periods of twenty, thirty, forty years or more. As a coating for steel, fireproofing may provide a good measure of corrosion protection. When applied directly to steel, concrete may passivate the steel surface by providing an elevated pH. Experience has shown, however, that passivation is less than certain, especially in coastal marine environments. Corrosion under concrete fireproofing can be significant. Intumescent coatings promise better corrosion protection than concrete by virtue of their low permeability but cases of severe corrosion under fireproofing (CUF) have been reported with these materials.
Intumescent epoxies are complex proprietary materials. Concrete and some of the other materials that are used for fire protection are more familiar. The materials themselves may seem simple, but the important details of system design are often overlooked.

Risk-Based Analysis

Fireproofing is a misnomer because no material is completely fireproof. All construction materials are subject to fire damage. What we really mean is fire resistant - we seek to resist potential fire situations for a given period of time. Fireproofing is passive, built-in protection that buys time to fight the fire, shut off the fire's fuel supply and shut down the process. The aim is to minimize the overall damage incurred.
The decision to fireproof is driven by risk-based analysis. One needs to first consider the nature of the fire threat and then make an assessment of the required period of fire endurance for a wide variety of equipment including structural steel, pressure vessels, heat exchangers, pipe supports, LPG spheres and bullets, valves, and cable trays. The location of specific equipment within a process unit is important, as is a unit's location with regard to neighboring facilities.

Test Methods and required Time Rating

No fire test method is going to be typical of a real fire situation and so, there is no single correct or "best" fire test method. Standardized testing simply provides a frame of reference for relative comparisons of fireproofing materials and designs.
In the 70s, ASTM E119 "Fire Test of Building Construction Materials" was the only internationally accepted standard for investigating the performance of fireproofing materials. This test method, however, was designed to measure the fire performance of walls, columns, floors, and other building members in solid fuel fire exposures. It does not simulate the high intensity of liquid hydrocarbon-fueled fires.
Where fireproofing is required, the level of fireproofing varies with the application in the plant. Typical protection requirements for a refinery or petrochemical plant might be as follows:

  • For structural steel, a facility may require a fire test rating of two or three hours. Poured-in-place concrete or gunite is most common with a specified minimum thickness of 2.0 to 3.0 inches (50-75 mm). Lightweight cementitious products may also be used.
  • For steel vessels, a facility may require a fire test rating of one to two hours. Gunite applied at 1.5 to 2.0 inches (40-50 mm) may be required. Alternative fireproofing materials that provide a comparable fire resistance rating may be used, including systems that function as both thermal insulation and fireproofing.
  • Plate and frame exchangers are a special concern because of the rubber gasketing material between plates. These exchangers are provided with a protective enclosure designed to prevent the exchanger from exceeding its maximum operating temperature for an hour or so. The maximum operating temperature is vendor specified and typically less than 300°F (150°C).
  • Electrical and pneumatic components (including manual initiators, valve actuators, aboveground wiring, cable, and conduit) essential to emergency isolation, depressurization, and process shutdown are generally fireproofed to achieve a rating of at least 15-20 minutes. This equipment needs to function properly in the first few minutes of a fire


Monday, December 15, 2014

Introduction to Fireproofing

Fireproofing, a passive fire protection measure, refers to the act of making materials or structures more resistant to fire, or to those materials themselves, or the act of applying such materials. Applying a certification listed fireproofing system to certain structures allows these to have a fire-resistance rating.

The term fireproof does not necessarily mean that an item cannot ever burn: It relates to measured performance under specific conditions of testing and evaluation. Fireproofing does not allow treated items to be entirely unaffected by any fire, as conventional materials are not immune to the effects of fire at a sufficient intensity and/or duration.

Fireproofing is employed in refineries and petrochemical plants to minimize the escalation of a fire that would occur with the failure of structural supports and the overheating of pressure vessels. The damage that fire could potentially do very early on, could add significant fuel to the fire.

The purpose of fireproofing therefore, is to buy time. The traditional method of fireproofing has been poured-in-place concrete or gunite. Other fireproofing materials, such as lightweight cements, prefabricated cementitious board, and intumescent coatings are used to a lesser extent, primarily in areas deemed less critical and where weight reduction is a significant benefit.


Friday, December 12, 2014

The Keys to Beating Corrosion: Early Detection and Expert Monitoring

As every industry professional knows too well, corrosion is a relentless and ever-present concern for the chemical process industry (CPI). 

In fact, corrosion is the main contributing factor to:
•Increased production costs
•Health and safety risks
•Environmental issues, and
•Legal liabilities. 

With the spread of corrosion presenting a daily threat in the CPI (Chemical Process Industries), it is important to constantly inspect and monitor equipment for early signs of corrosion to prevent costly repairs or equipment failure later.

The effects of corrosion are startling:

•“As of 2014, the annual cost of corrosion in the U.S. is estimated to be about $1 trillion (about 6% of the gross domestic product).”
•“For the petrochemical sector, the annual cost is about $1.7 billion.”
•“The annual cost in the CPI is over 8% of the annual plant capital expenditures across these industrial sectors.”
Not only does corrosion cost the CPI substantial amounts of money, it also reduces the operating life of equipment, which in turn reduces the value of assets. There are many different methods to inspecting corrosion. The following methods help to locate the problems and can keep you aware of the type and location of corrosion.

Methods of detecting corrosion:

•API Visual Inspection
•Magnetic Particle Flaw Detection
•Ultrasonic Inspection
•Dye Penetrants
•Remote Visual
•Bracelet Probe (CUI)
•Moisture Detection (CUI)
•Eddy Current
•Risk Based Inspection (RBI)

Monitoring corrosion is used to closely watch areas with signs of corrosion in all critical components. There are also several methods for monitoring corrosion.

Methods of monitoring corrosion:

•Ultrasonic Testing
•Radiographic Testing
•Guided Wave Testing
•Electromagnetic Testing
•Advanced Laser Testing (ALT)
•X-Ray (Computed Radiography)


Friday, December 5, 2014

Cost of Corrosion Annually in the US Over $1 Trillion

Corrosion will cost the US economy over $1 trillion in 2014. That’s one of the largest expenditures NACE Corrosion Costs Study. However, this report leaves out the enormous (at least as much as direct costs) tally of indirect costs that the consumers experience from corrosion and the inflation increases since 1998.
we make, and it’s all going down the drain. The total annual corrosion costs in the U.S. rose above $1 trillion in the middle of 2013, illustrating the broad and expensive challenge that corrosion presents to equipment and materials. The most commonly quoted figure for corrosion costs is $276B in 1998 and was reported in the
From $276B to $1 Trillion: Understanding the Real Cost of Corrosion
The NACE sponsored report examines each industry in depth, providing discussions of the causes, costs, and results of corrosion, and arrived at a figure of $276B in direct corrosion costs. Indirect costs were estimated to be at least as much as direct costs.  In the 15 years that have passed since the study was released, inflation has driven both the direct and indirect costs of corrosion over $500 billion annually, totalling over $1 trillion in 2013.
At over 6.2% of GDP, corrosion is one of the largest single expenses in the US economy yet it rarely receives the attention it requires. Corrosion costs money and lives, resulting in dangerous failures and increased charges for everything from utilities to transportation and more. For a more thorough breakdown of specific corrosion costs by industry, see the NACE Corrosion Costs Study(and approximately double the numbers to have a good estimate of current values).
About the author: Dr. Jackson is part of G2MT Labs, a company at the cutting-edge of new technologies that promise to dramatically reduce the costs (both economic and social) of corrosion.