5 Critical Success Factors for Effective BOMs

No company engaged in manufacturing business of pumps,compressors,turbines, automobiles, appliances, iPads, or even cardboard boxes,etc. can think about scheduling production without a complete and accurate Bill of Materials (BOM) for each finished product so they could  determine their raw material requirements from a master schedule. So why is it that many process industries not only begin operation without equipment BOMs, but go for years, sometimes decades, without them?
Have they ever analysed the cost of maintenance and repair per tonne of production associated with such sustenance without BOMs?

When we ask plant maintenance engineers to assess the quality and adequacy of their equipment BOMs, the comments we get most often are either, “they don’t exist,” or, “we have some of the data, but we don’t know if it’s accurate.” When we ask why that’s the case, the response is usually, “we don’t have the information,” or more likely, “we don’t have the resources to do all that work.”

So instead of taking the time to build and maintain the BOMs, they just go on without them. That means planners, maintenance and reliability engineers, mechanics, materials management and procurement personnel, and others have to go outside the system to do things like:

• Determine material requirements for planned work
• Query and locate parts for emergency and other unplanned work
• Associate critical spares to specific assets
• Evaluate part substitutions
• Assess non-moving material for obsolescence
• Identify opportunities for part standardization Somehow there’s time for most of these workarounds, and although it’s hard to calculate, it probably takes 2 to 10 times as much effort to deal with the lack of information as it would to just fix the problem in the first place. Unfortunately the focus is on the reactive aspects of what really needs to be done and not on the proactive aspects of getting the information into the system. If you don’t keep up, it’s hard to catch up. So what are the five critical success factors for establishing and maintaining effective BOMs?

1. There’s no question that the #1 thing you can do is get the information into the system as early as possible! As soon as you have made a commitment to buy a new piece of equipment, you should be on the phone with the manufacturer or supplier to get the BOM information. Unless there’s a possibility that something could change, there’s no reason not to have the BOM data in the system even BEFORE the equipment is installed.
2. Don’t kill yourself trying to get every last little item into the database. If your system supports an automatic upload of BOM data from an electronic file, then take advantage of it. But if you have to enter the data manually, make sure you enter the most important items first. Another rule of thumb is: anythingyou reasonably expect to repair and/or replace should go on the BOM, with the exception of consumables and free issue parts.
3. Make sure you have a robust process in place to manage changes to the asset base. Whether you call it “Management of Change,” “Configuration Management,” the important thing is that all equipment redesigns, material changes, part substitutions, or even significant modifications are assessed to determine the impact on the BOM.
4. Don’t forget about retired assets. How many times have you had someone look at an expensive or supposedly critical part that hasn’t moved in the storeroom and heard them say, “oh, we stopped using those years ago when we took out the whatever.” It’s so much easier (not to mention cost effective) to deal with these situations as they occur.
5. Make it part of the culture. This isn’t something that can be done randomly or easily driven from the bottom up. It requires management commitment to make it a priority, with clearly defined responsibilities and expectations for each person involved in establishing and maintaining the integrity of the BOMs, and accountability for making sure it happens.

Risk-Based Inspection (RBI) to identify CUI

 The purpose of RBI is to identify susceptible pressure vessels, piping and fireproofed structural supports subject to CUI/CUF, to prioritize inspections, and to develop an inspection plan to reduce risk.

1. The information needed to assess the likelihood of failure due to CUI or CUF damage includes, but is not limited to:
• Specific site environment
• Material of construction
• Age of component
• Operating process temperature
• Exposure to intermittent/cyclic service
•  Areas with missing insulation
• Age of insulation/fireproofing
• Type of coating present, if any
• Age of coating
• Presence and condition of steam tracing
This data can be obtained from a variety of sources, and can include the original engineering records, Management of Change (MOC) database, maintenance work order records, and inspection records. Other data, which pertains to the physical condition of the component, can be obtained from a field inspection. These inspections can be incorporated into the external inspection programs, or may be part of a special emphasis CUI inspection project.
2. Prior to conducting the assessment, the atmospheric environment of the area being assessed within the plant needs to be classified. Examples of atmospheric environment descriptors included in API RP 581 are arid/dry area, temperate area, severe area, arid marine/cooling tower drift area.
3. Due to the highly localized nature of damage, CUI and CUF assessments lend themselves to a qualitative assessment approach to assess the likelihood of failure.
3.1 The owner/user may modify (i.e. add or eliminate) the number of parameters, change the description of individual parameter categories, modify the value of individual parameter ratings, increase or decrease the minimum or maximum range of individual parameters, or the total number of likelihood rating categories to address company or site-specific factors.
4. The owner/ user should consider the differences between potential failure modes for each of the damage mechanisms when assessing consequence. Namely,
• Corrosion hole from CUI (most frequently a small leak)
• Cracking for ECSCC of austenitic/duplex stainless steels (most frequently a small leak)
• Rupture/Structural instability (rare event)
It should be recognized that while many CUI leaks occur from smaller pits, a number of CUI loss of integrity events have occurred as a result of larger locally thinned areas. The owner/user should assess the consequence of both types of risks in the risk assessment process.
5. Consequence assessment should conform to the documented site consequence assessment process. Guidance on RBI consequence assessment can be found in API RP 580 and 581. Though CUI damage is most often likely to produce an equipment reliability issue, in rare cases, safety and environmental issues can arise.

AREAS SUSCEPTIBLE TO CUI or CUF DAMAGE

Under the right temperature conditions, CUI or CUF damage can occur at any location that is insulated or fireproofed. CUI and CUF are somewhat insidious in that regard. It is not uncommon to find CUI/CUF damage in locations remote from the more predictable and susceptible locations. However, there are some areas within facilities that  have higher susceptibility for damage. In general, areas with severe CUF damage are easier to identify visually than CUI damage due to cracks and staining of the fireproofing. Certain areas and types of equipment have a higher susceptibility for CUI damage.
1.1 General Areas of DamageThere are a number of locations in oil or chemical processing facilities where CUI damage has a higher likelihood.
Potential locations areas  for CUI throughout Process Facilities common to all equipment type are:

• Areas downwind of cooling towers exposed to cooling tower mist
• Areas of protrusions (i.e. transition points) through the jacketing at manways, nozzles, and other components
• Areas of protrusions through insulation for equipment/piping operating at below ambient or cold service
• Areas where insulation jacketing is damaged or missing
• Areas where caulking on insulation jacketing is missing or hardened
• Areas in the jacketing system are bulged or stained
• Areas where banding on jacketing is missing
• Areas where thickness monitoring plugs are missing
• Areas where vibration has caused damage to the insulation jacketing
• Areas exposed to steam vents
• Areas exposed to process spills, ingress of moisture, or acid vapors
• Areas exposed to deluge systems
• Areas insulated solely for personnel protection
• Areas under the insulation with deteriorated coatings or wraps
• Areas with leaking steam tracing
• Pipe and flanges on PSV’s
• Systems that operate intermittently above 250°F (120°C)
• Systems operating below the atmospheric dew point
• Systems that cycle through the atmospheric dew point
• Ice-to-air interfaces on insulated systems which continually freeze and thaw are susceptible to corrosion damage

All equipment will be shut down at some time or other. The length of time and the frequency of the down time spent at ambient temperature may well contribute to the amount of corrosion under insulation that occurs in the equipment.

1.2 Pressure Vessels

In addition to the areas listed above, there are other areas in vessels, columns, drums, and heat exchangers where CUI may have a higher likelihood..

 Potential locations are:

• Insulation support rings below damaged or inadequately caulked insulation on vertical heads and bottom zones
• Stiffening rings on insulated vessels/columns in vacuum service
• Insulated zone at skirt weld
• Insulated leg supports on small vessels
• Ladder and platform attachments
• Termination of nozzle and saddle insulation
• Fireproofed skirts (CUF)
• Anchor bolts (CUF)
• Bottom of horizontal vessels
• Irregular shapes that result in complex insulation installations (e.g., davit arm supports, lifting lugs, body flanges, etc.)

1.3 Piping

In addition to the areas listed under point no1.1 above , there are other areas in piping where CUI may have a higher likelihood, and includes process piping, refrigerated piping, piping at or below grade, and pipe supports. 

Susceptible Potential locations for CUI and CUF in piping are :

• Deadlegs, vents, and drains
• Pipe hangers and supports
• Valves and fittings
• Bolted on pipe shoes
• Steam/electric tracing tubing penetrations
• Termination of insulation at flanges and other piping components
• Carbon/low alloy steel flanges, bolting, and other components in high alloy piping
• Jacketing seams on the top of horizontal piping
• Termination of insulation on vertical piping
• Areas where smaller branch connections intersect larger diameter lines
• Low points in piping with breaches in the insulation

1.3.1 Cold piping

 Cold piping is piping used to deliver liquid or gases which cools the piping to temperatures below the atmospheric dew point. Cold piping is prone to corrosion due to condensation. The condensation present will most likely freeze in cases where the outside surface of the piping decreases below freezing. In many cases, such as ammonia terminals, piping temperature swings from ambient to -30°F (-27°C) during periods when ammonia is flowing in the piping. This temperature swing leads to continuous freezing and thawing resulting in wet conditions that increases the piping system susceptibility to CUI damage. Additionally, other equipment and components such as tanks, pressure vessels, pipe supports and flanges connected by this piping may be affected by the run off of melting ice.

Ice layers can form on piping operating at temperatures below freezing, and can obscure the view of external surface damage due to a continuous wet environment. In many cases, piping used for these cold temperature applications is insulated. Frequent chilling and condensation accelerates corrosion at points where insulation is breached which exposes the surface of the piping to the atmosphere (i.e., ice-to-air interfaces). Water ingress, due to poorly sealed insulation jacketing, can result in ice build-up causing swelling of the insulation, and create a larger area of damage to the insulation system. This repeated condition creates more and more exposure and susceptibility to corrosion.

Frequent chilling and condensation accelerates corrosion at points where insulation is breached which exposes the surface of the piping to the atmosphere (i.e., ice to air interfaces). Water ingress, due to poorly sealed insulation jacketing, can result in ice build-up causing swelling of the insulation thus creating a larger damaged area to the insulation system; this repeated condition creates more and more exposure and susceptibility to corrosion.

Susceptible locations for CUI/CUF in Piping Operating Below the Dew Point

• Pipe Supports
• Insulation termination areas such as pipe to flanges
• Flanges with stud bolts where insulation bonnets are installed but not sealed
• Piping below flood grade where rising water penetrates the insulation jacketing causing ice lens with swelling which causes jacketing failure
• High foot traffic areas where insulation is degraded by contact with human traffic
• Ice-to-air interface

1.3.2 Pipe supports
The accumulation of water can occur at locations remote from the point of intrusion, especially in services where the surface temperature does not cause the water to evaporate. For example, this can occur on a horizontal line in the middle of a span between pipe supports where the insulation is missing at the supports. Yet, evaporated water may also travel through the insulated system and condense in areas with a lower surface temperature.

1.4 Tankage and Spheres

This includes insulated tanks and spheres in both hot and cold service.
Susceptible locations for CUI and CUF damage in various equipment types are 

• Stairway tread attachments
• Insulation support rings
• Fireproofed legs on spheres (CUF)
• Insulation penetrations such as nozzles, brackets, etc. on shell and roof

1.5 Heat Traced Systems

Heat tracing systems are used to protect pipes from freezing, or to maintain process temperatures for piping that should transport substances that solidify or lose viscosity at ambient temperatures. Heat traced systems are divided between electric and steam traced systems. From a design perspective, electric traced systems with chloride-free (i.e. non-PVC) electrical insulation would be the preferred choice to minimize CUI damage in insulated systems. Though this may be the preferred choice to minimize CUI damage, in reality, the majority of systems in use today are steam traced systems.

When steam tracing  fails, it defeats all CUI barriers. These systems often fail at coupling joints under the insulation. When steam tracing fails under insulation, it introduces moisture, strips away protective coatings, and raises the metal surface temperature within the CUI temperature regime. In addition, the same conditions can potentially cause ECSCC on austenitic stainless steel pipe and instrument tubing under the insulation.

1.6 Shutdown/Mothballing

Equipment or piping systems that are shutdown for extensive periods or mothballed also have higher susceptibility for CUI and CUF damage. During extended idle periods, these weather barriers, i.e. insulation and fireproofing, can deteriorate and lead to increased corrosion . Consideration should be given to removing insulation and fireproofing on equipment and piping systems that are shutdown for extended periods of time or as part of the mothballing procedure, especially in moist and humid climates.

Evaluation Phase for Removal of Insulation from Equipment in service for CUI inspections.

As part of an insulation removal evaluation phase, the following list of questions may be helpful for review prior to executing CUI inspections:
• Is equipment/piping in cyclic service? If ‘yes’, what are the maximum temperatures expected, and duration of maximum temperature?
• Is equipment/piping in Intermittent Service? If yes, what is the frequency of operation?
• Is equipment/piping subject to steaming and/or hot gas treatment? If yes, what is the frequency? Maximum temperature and the duration?
• Can the insulation be removed for CUI inspection and remediation while the equipment/piping is in service without adversely affecting process control and product quality?
• Is equipment/piping currently Out-of-Service?
• Is insulation installed for the sole purpose of personnel protection (> 140 F)? If yes, can metal cages or ceramic coatings be used instead of insulation?
• Does the equipment/piping contain fluids that may freeze resulting in an interruption of service(s)?
• Does the equipment/piping need insulation for process control/unit production? If yes, would wind and rain guards suffice?
• Does the equipment/piping require heat tracing? If yes, is the heat tracing used continuously or only if certain conditions exist?
• Does the equipment/piping require insulation to reduce condensation?
• Does the equipment/piping require insulation for acoustics?
• Does the equipment/piping require insulation for fire protection or controlling pressure relieving events?
• Do the heat conservation economics dictate this equipment/piping be insulated? [Usually considered at > 200°F (>95°C).

Insulating Materials used in Petrochemicals/Refinery

Thermal insulation is important to facility operations, yet is often overlooked and undervalued. These materials can be used in either low- or high-temperature applications. For refinery and petrochemical plant applications, insulation materials can be classified into one of the three categories listed below:
• Granular
• Fibrous
• Cellular
1. Granular-type Insulations
Granular insulations are composed of small nodules that contain voids or hollow spaces. These materials are sometimes considered open-cell materials since gases can be transferred between the individual spaces. Calcium silicate and molded perlite insulations are considered granular insulations.

1.1 Calcium Silicate
Calcium silicate insulation is a rigid pipe and block insulation composed principally of calcium silicate and usually incorporates a fibrous reinforcement. It is intended for use in high temperature applications. If immersed in water at ambient temperatures, the material can absorb significant amounts of water (i.e. up to 400% by weight). Even when not immersed in water, the material can absorb up to 25% by weight water in high humidity conditions due to its hygroscopic nature. When exposed to water, the material has a pH of 9-10 and may be detrimental to coatings on metal surfaces. Additionally, some manufacturers offer products with controlled or low chloride levels for specialty applications. The advantages and disadvantages for calcium silicate insulation are listed below:
a) Advantages
-   Low thermal conductivity (when dry)
- Suitable for temperatures to 1000°F (538°C) continuously or 1200°F (650°C) intermittently.
- Available in a variety of shapes/sizes
- Available with low chloride levels
b) Disadvantages
- Will readily absorb moisture
- Silica dust created during cutting  may be carcinogenic
- Fragile (i.e. brittle). Care needed to avoid breakage during installation

1.2 Expanded Perlite
Perlite is a volcanic rock containing from 2 to 5 percent bonded water. It is a chemically inert substance composed basically of silica and aluminum. The perlite is expanded by means of rapid heating at a temperature between 1475°F and 2200°F (800°C and 1200°C). The vaporization of the bonded water and the formation of natural glass results in the expansion of the perlite particles. These particles have a granular shape.
Expanded perlite insulation is either rigid pipe or block insulation composed of expanded perlite, inorganic silicate binders, fibrous reinforcement, and silicone water-resistant additions. These silicone additions provide protection from water absorption at temperatures below 600°F (315°C). The water resistance of the material is reduced at or above this temperature. Similar to calcium silicate, some manufacturers offer expanded perlite products with controlled or low chloride levels for specialty applications. The advantages and disadvantages for expanded perlite insulation are listed below:
a) Advantages
- Water resistant up to 400°F (205°C)
- Good resistance to mechanical damage
- Available in a variety of shapes/sizes
b) Disadvantages
- Slightly more fragile than calcium silicate during installation
- Perlite dust can cause chronic poisoning
- Higher thermal conductivity than calcium silicate

2. Cellular-type Insulations
Cellular insulations are classified as either open cell structures where the cells are interconnecting, or closed cell structures where the cells are sealed from each other. Generally, materials that have greater than 90 percent closed-cell content are considered to be closed-cell materials.
2.1 Cellular Glass
Cellular glass (also referred to as foam glass) is a closed-cell insulation composed predominantly of silica-based glass. It is made by adding powdered carbon to crushed glass and firing the mixture to form a closed cell structure. It is commonly used on electric-traced or steam-traced piping for freeze protection or process control.
The low permeability and absorption characteristics of cellular glass make it an attractive choice for cold service and cryogenic applications. This insulation material does not wick water or liquids, and is used in hot service where the non-absorbent/non-wicking properties are desirable. The material has a thermal conductivity rating between mineral wool and calcium silicate, and displays good compressive strength. It can be friable and brittle when subjected to mechanical abuse, and can crack when subjected to large temperature differences and thermal shock.
Cellular glass has the chemical resistance of glass. Cellular glass systems have been designed for applications operating at temperatures from -450°F to 800°F (-260°C to 427°C). The material can suffer vibration-induced damage, and can also be prone to damage when boiling water is trapped between the pipe and the insulation. Stress relief cracking of cellular glass can also occur at service temperatures above 450°F to 500°F (230°C to 270°C). The manufacturer should be consulted for the best method for insulating systems operating above 450°F (230°C).
The advantages and disadvantages for cellular glass insulation are listed below:
a) Advantages
- Does not absorb water
- High resistance to mechanical damage when jacketed
- Thermal conductivity does not deteriorate with aging
b) Disadvantages
- Susceptible to thermal shock if temperature gradient >300°F (>150°C)
- Easily abrades in vibrating service, and fragile before application
- Higher price when compared to other insulation types

2.2 Organic Foams
This category of insulation materials includes polyurethane, polyisocyanurate, flexible elastomeric, polystyrene, and phenolic insulations. Except for flexible elastomeric insulation, they are classified as either rigid/closed-cell foams or flexible/closed-cell foams. Flexible elastomeric insulation is classified as an a flexible/closed-cell foam. These materials contain chlorides, fluorides, silicates, and sodium ions which can be leached from the insulation at temperatures above 212°F (100°C). The leachate produced can have a wide range of pH (i.e. 1.7 to 10.0). Accelerated corrosion can take place when the pH of the leachate is below 6.0.
2.2.1 Polyurethane Foam
Polyurethane foam is an organic, closed-cellular foam that can be installed by spraying or casting in the shop or field. Pre-cast pieces are also available. Closed-cell foams are structures where all of the tiny foam cells are packed close together with no interconnected pores. The foam cells are filled with a low-conductivity gas, usually hydrochlorofluorocarbon (HCFC), which helps the foam to rise and expand. It is an insulation product that is produced on-site, and is typically applied by certified applicators. Two liquid components, an organic isocyanate compound (i.e. diisocyanate) and an alcohol (i.e. polyol) are mixed at high or low pressure using a spray gun with the reacting mix being sprayed onto the substrate to provide a seamless seal.
Polyurethane foam is frequently used for pre-insulated pipe joints. It has low permeability and absorption characteristics, but can absorb water after prolonged service. A typical design range for polyurethane foam is from -150°F to 275°F (-65°C to 135°C). The advantages and disadvantages for polyurethane foam insulation are listed below:
a) Advantages
- Low permeability and absorption characteristics (closed cell)
- Multiple product forms and easy to apply in the field
- Provides a seamless seal
b) Disadvantages
- Can be ignited and release toxic gases if exposed to an open flame.
- Sensitivity to UV radiation (sunlight)
- Can be vulnerable to some acids, caustics, solvents, hydrocarbons, and other chemicals

2.2.2 Polystyrene Foam
There are two categories of polystyrene foam insulation, 1) expanded polystyrene foam (EPS), and 2) extruded polystyrene foam (XPS).
Expanded polystyrene (EPS) foam is a closed-cell insulation that is manufactured by expanding a polystyrene polymer. It is usually white, and made of pre-expanded polystyrene beads. It is an aromatic, thermoplastic polymer made from the monomer styrene which is in solid (glassy) state at room temperature. When heated above  212°F (100°C), it flows sufficiently to permit molding or extrusion, becoming a solid when cooled.
Extruded polystyrene (XPS) is a rigid, closed-cell insulation manufactured from solid polystyrene crystals. The crystals are fed into an extruder along with special additives and a blowing agent and melted into a viscous plastic fluid. After being forced through the extrusion die, the hot, thick liquid expands to become a foam which is shaped, cooled, and trimmed to dimension. This continuous extrusion process produces a uniform closed-cell structure with a smooth continuous skin.
The advantages and disadvantages for polystyrene foam insulation are listed below:
a) Advantages
- Excellent resistance to water and water absorption from freeze/thaw cycling
- Very stable and does not biodegrade for hundreds of years
- Resistant to photolysis
b) Disadvantages
- Like other organic compounds, polystyrene is flammable.
- When burned without enough oxygen or at lower temperatures, polystyrene can produce a number of chemicals including polycyclic aromatic hydrocarbons, carbon black, and carbon monoxide, as well as styrene monomers which can irritate eyes, nose, and respiratory system.
- Primarily a cold system insulation material, melting point is approximately 465°F (240°C).
2.2.3 Polyisocyanurate Foam
Polyisocyanurate is an organic, closed-cellular, rigid foam. It has low permeability and absorption characteristics, and is typically used in cold service applications. The material is flexible and has reasonable strength to provide resistance to light physical abuse. It has a lower thermal conductivity than mineral wool insulations. A typical design temperature range is -297°F to 300°F (-150°C to 150°C). Disadvantages include combustibility and sensitivity to UV radiation (sunlight). Combustion may release toxic gases. Chemical resistance is generally good but can be vulnerable some acids, caustics, solvents, hydrocarbons and other. The advantages and disadvantages for of polyisocyanurate foam insulation are listed below:

a) Advantages
- Low permeability and absorption characteristics
- Multiple product forms and easy to apply in the field
b) Disadvantages
- Like other organic compounds, polyisocyanurate is flammable.
- Primarily a cold system insulation material
- When burned without enough oxygen or at lower temperatures, a number of chemicals are produced which can irritate eyes, nose, and respiratory system

3. Fibrous-type Insulations
This category of insulation materials includes mineral wool and fiberglass insulation. These materials are processed from molten state into fibrous form and combined with organic binders and pressed into rolls or sheets. The fiber length, fiber orientation, and type of binder used impact the ability of these materials to repel water. Upon breakdown of the binder, the wicking ability of these materials increases significantly and transmits moisture or corrosive solutions to the underlying surface. Mineral wools are unattractive to rodents but will provide a structure for bacterial growth if allowed to become wet.
3.1. Mineral Fiber
Mineral fiber insulations are composed principally of fibers manufactured from rock, slag, or glass, with or without binders. Molten glass, stone or slag is spun into a fiber-like structure. Inorganic rock or slag is the main components (typically 98%) of stone wool. The remaining 2% organic content is generally a thermosetting resin binder (an adhesive) and a little oil. Though the individual fibers conduct heat very well, when pressed into rolls and sheets their ability to partition air makes them excellent heat insulators and sound absorbers. Mineral fiber insulation is commonly used in hot applications up to 1200°F (650°C). Mineral fiber has a lower thermal conductivity than calcium silicate and perlite. However, even with metal jacketing, mineral fiber is subject to mechanical damage due to its low compressive strength and lack of resiliency. This can lead to reduced insulation thickness and possibly open jacket seams where the jacket has been crimped. If used at an elevated temperature, the organic binder that helps to hold the fibrous insulation together is burned away causing a further reduction in strength.
Fibrous insulations are readily permeable to vapors and liquids. For this reason, fibrous insulation is not used alone for low temperature applications where condensation can occur. Most fibers will readily wick hydrocarbons and water. Sometimes hydrophobic treatments or coatings are applied to the insulation by manufacturer to reduce water absorption and wicking. These coatings do not eliminate water saturation when immersed and the coating effectiveness may degrade in-service after exposure to higher temperatures.
The advantages and disadvantages for mineral wool insulation are listed below:
a) Advantages
- Used  in hot applications up to 1200°F (650°C)
- Has a lower thermal conductivity than calcium silicate and perlite
- Low leachable chloride content (< 5ppm)
b) Disadvantages
- Fibrous insulations are readily permeable to vapors and liquids.
- Most fibers will readily wick hydrocarbons and water
- Mineral fiber is subject to mechanical damage due to its low compressive strength and lack of resiliency
3.2. Fiberglass
Fiberglass is widely used as industrial insulation. Fiberglass is mechanically weak like mineral fiber and shares the same disadvantages with respect to wicking and permeability. Maximum use temperature is typically less than 850°F (455°C) with some users specifying a temperature maximum of 450°F (230°C) due to binder burnout. The advantages and disadvantages for fiberglass insulation are listed below:
a) Advantages
- Noncombustible
b) Disadvantages
- Compressing the material reduces its effectiveness
- Absorbs water
- Can cause skin  allergies
3.3. Silica Aerogel
Silica aerogel is a synthetically produced amorphous silica gel which is distinctly different from crystalline silica. It is impregnated into a non-woven flexible fabric substrate (i.e. batting) for reinforcement. Aerogels are good thermal insulators because they almost nullify convective, conductive, and radiative heat transfer. Silica aerogels have an extremely low thermal conductivity ranging from 0.03 W/m·K to 0.004 W/m·K which correspond to R-values of 14 to 105 for 3.5 inch thickness. Product forms can be as a flexible mat/blanket and include integral vapor barriers. The advantages and disadvantages for silica aerogel insulation are listed below:
a) Advantages
- Highest thermal performance of any insulating material known
- Significantly reduced thickness for equivalent performance to other insulating systems
- Wide range of temperature applications (may require a change in specific product to cover hot or cold insulation)
b) Disadvantages
- Aerogels are typically hygroscopic
- Need chemical treatment to be hydrophobic
- Typically higher cost of materials (installed cost and performance may provide economic benefits in long run)