GENERAL
All repairs should be made in clean, dry and well-ventilated conditions. When repairs are made outside, the repair area should be protected with suitable covers to provide shade from the sun or protection from rain. If the relative humidity is greater than 70% or the ambient temperature is less than 15 C (60 F) then a heated protective enclosure should be used to bring the ambient conditions around the repair within these limits.

Resins, catalysts, and other chemicals should not be stored in temperature conditions above 21 C (70 F) for maximum shelf life. Freezing temperatures do not adversely affect resins and catalysts, but the temperatures of these materials should be brought up to at least 20 C (68 F) prior to use. Reinforcing material should be kept in plastic bags to prevent contamination from dirt and moisture until required for the repair work.

1. Liquid resin, catalysts, and solvents are flammable materials and must be kept away from open flames or other sources of ignition. Observe no smoking rules when handling these materials and mark containers accordingly.
2. Safety glasses and a dust mask should be worn during any cutting or grinding operations.
3. Safety glasses should be worn when mixing chemicals to prevent any splashes from contacting the eyes.
4. Any prolonged skin contact with resins may cause irritation and should be washed off with soap and water as soon as possible.
5. Any skin contact with promoters or catalysts should be washed off with soap and water immediately.
6. Any eye contact with resins, promoters or catalysts should be flushed with flowing water for 15 minutes and medical attention sought immediately.

EQUIPMENT
The following is a list of commonly used equipment for field repair work:

MATERIALS

RESIN AND CATALYST:
Promoted polyester resins are normally used for all field repair work. As a rough guide for the quantity of resin needed for a repair, one half litre of resin will saturate one half-square metre of 450 g/sq. chopped strand mat or one square metre of 800 g/sq.m. woven roving. (5 sq.ft. of 1-1/2% methyl ethyl ketone peroxide (MEKP) by weight or resin. This will give a gel time between 15 and 60 minutes depending on ambient temperature, catalyst type and resin type. Specific recommended catalyst levels are available from resin suppliers for all available resins. A reasonable quantity of resin to work with at the start of a repair is one half litre (1 pint). This will give a good indication of the gel time or working time that can be expected from the catalyst system used and in the ambient conditions of the repair work. The mix quantity and catalyst level can then be adjusted to suit requirements of the repair work.

Under high temperature working conditions the catalyst level can be reduced to provide a longer working time before the resin begins to gel, but the catalyst level should not go below 1/2% by weight of the resin or a complete cure will not be achieved. In cases when sufficient working time cannot be achieved with lower catalyst levels the promoted resin can be mixed with non-promoted resin of the same kind to effectively reduce the promotion level, extend the working time, and still achieve a good cure.

Under low temperature working conditions, supplemental heat may be required. It is common practice to use electric heating elements or heat lamps for this purpose. Combustion type heaters present an explosion hazard and a possible contamination source of both the working atmosphere and the surface of the laminate being repaired. Care must also be taken to ensure that the heaters do not overheat the laminate during cure.

RESIN AND CATALYST:

For relatively thin surface coats the catalyst level is commonly increased to around 2% to increase the exothermic temperature and obtain a better cure in spite of the small mass of resin. Exterior surface coats are normally applied with a resin containing a wax type of air inhibiting additive. Without this additive, the surface of the resin will not cure completely due to a reaction with oxygen in the air and the surface will remain tacky even though the resin below it is completely cured.

Interior surface coats that are exposed to corrosive environments are normally covered with cellophane or Mylar film to assure complete cure of the resin without using a wax additive.

GELCOTE

Gelcote is the coloured resin used on the finished surface. Handling characteristics and catalyzation is the same as per the resin section. NPG gelcotes are recommended for exterior uses for increased weatherability.

RESIN PASTES OR PUTTY

It is common practice in the industry to use resin pastes or putty to fill gaps and crevices in laminates. In general this is not a good practice but it is unavoidable in many situations. Pastes are primarily used for cosmetic repairs or filling cavities prior to laminating.
In areas where the cured paste is not directly in contact with the corrosive environment, a commercially available compound (carpatch) may be used.

REINFORCEMENTS

Commonly used glass reinforcements for field repair work includes 450 g/sq. chopped strand mat and 800 g/sq. woven roving. The reinforcing materials used for repair work must be clean, dry, and of good quality. All the reinforcing materials used for a particular repair job should be cut to the size required and stacked in the sequence in which they will be used. These materials should then be placed in a moisture proof package until required for the repair work.

A general practice used in the industry, is to place a layer of chopped strand mat between layers of woven roving to improve the shear strength between the woven roving layers in the laminate.

TRIMMING AND CUTTING

The best equipment for cutting materials is an abrasive type disc. Diamond impregnated discs generally give a cleaner cut edge and longer disc life. For smaller jobs and for trimming, sabre saws and fine toothed hacksaws are often used. Wherever possible the cutting tool should cut into the face of the corrosion liner, as opposed to away from the face, to minimise excessive chipping of the liner at the cut edge.

For repairs of damaged laminates, all the damaged material should be cut away in preparation for the repair.

MATERIAL PREPARATION

The amount and size of reinforcing material required will be determined by the extent of the damaged area. There are many combinations of wall constructions and loading conditions for equipment, which make it very difficult to provide specific

GENERAL
All repairs should be made in clean, dry and well-ventilated conditions. When repairs are made outside, the repair area should be protected with suitable covers to provide shade from the sun or protection from rain. If the relative humidity is greater than 70% or the ambient temperature is less than 15 C (60 F) then a heated protective enclosure should be used to bring the ambient conditions around the repair within these limits.

Resins, catalysts, and other chemicals should not be stored in temperature conditions above 21 C (70 F) for maximum shelf life. Freezing temperatures do not adversely affect resins and catalysts, but the temperatures of these materials should be brought up to at least 20 C (68 F) prior to use. Reinforcing material should be kept in plastic bags to prevent contamination from dirt and moisture until required for the repair work.

1. Liquid resin, catalysts, and solvents are flammable materials and must be kept away from open flames or other sources of ignition. Observe no smoking rules when handling these materials and mark containers accordingly.
2. Safety glasses and a dust mask should be worn during any cutting or grinding operations.
3. Safety glasses should be worn when mixing chemicals to prevent any splashes from contacting the eyes.
4. Any prolonged skin contact with resins may cause irritation and should be washed off with soap and water as soon as possible.
5. Any skin contact with promoters or catalysts should be washed off with soap and water immediately.
6. Any eye contact with resins, promoters or catalysts should be flushed with flowing water for 15 minutes and medical attention sought immediately.

EQUIPMENT
The following is a list of commonly used equipment for field repair work:

MATERIALS

RESIN AND CATALYST:
Promoted polyester resins are normally used for all field repair work. As a rough guide for the quantity of resin needed for a repair, one half litre of resin will saturate one half-square metre of 450 g/sq. chopped strand mat or one square metre of 800 g/sq.m. woven roving. (5 sq.ft. of 1-1/2% methyl ethyl ketone peroxide (MEKP) by weight or resin. This will give a gel time between 15 and 60 minutes depending on ambient temperature, catalyst type and resin type. Specific recommended catalyst levels are available from resin suppliers for all available resins. A reasonable quantity of resin to work with at the start of a repair is one half litre (1 pint). This will give a good indication of the gel time or working time that can be expected from the catalyst system used and in the ambient conditions of the repair work. The mix quantity and catalyst level can then be adjusted to suit requirements of the repair work.

Under high temperature working conditions the catalyst level can be reduced to provide a longer working time before the resin begins to gel, but the catalyst level should not go below 1/2% by weight of the resin or a complete cure will not be achieved. In cases when sufficient working time cannot be achieved with lower catalyst levels the promoted resin can be mixed with non-promoted resin of the same kind to effectively reduce the promotion level, extend the working time, and still achieve a good cure.

Under low temperature working conditions, supplemental heat may be required. It is common practice to use electric heating elements or heat lamps for this purpose. Combustion type heaters present an explosion hazard and a possible contamination source of both the working atmosphere and the surface of the laminate being repaired. Care must also be taken to ensure that the heaters do not overheat the laminate during cure.

RESIN AND CATALYST:

For relatively thin surface coats the catalyst level is commonly increased to around 2% to increase the exothermic temperature and obtain a better cure in spite of the small mass of resin. Exterior surface coats are normally applied with a resin containing a wax type of air inhibiting additive. Without this additive, the surface of the resin will not cure completely due to a reaction with oxygen in the air and the surface will remain tacky even though the resin below it is completely cured.

Interior surface coats that are exposed to corrosive environments are normally covered with cellophane or Mylar film to assure complete cure of the resin without using a wax additive.

GELCOTE

Gelcote is the coloured resin used on the finished surface. Handling characteristics and catalyzation is the same as per the resin section. NPG gelcotes are recommended for exterior uses for increased weatherability.

RESIN PASTES OR PUTTY

It is common practice in the industry to use resin pastes or putty to fill gaps and crevices in laminates. In general this is not a good practice but it is unavoidable in many situations. Pastes are primarily used for cosmetic repairs or filling cavities prior to laminating.
In areas where the cured paste is not directly in contact with the corrosive environment, a commercially available compound (carpatch) may be used.

REINFORCEMENTS

Commonly used glass reinforcements for field repair work includes 450 g/sq. chopped strand mat and 800 g/sq. woven roving. The reinforcing materials used for repair work must be clean, dry, and of good quality. All the reinforcing materials used for a particular repair job should be cut to the size required and stacked in the sequence in which they will be used. These materials should then be placed in a moisture proof package until required for the repair work.

A general practice used in the industry, is to place a layer of chopped strand mat between layers of woven roving to improve the shear strength between the woven roving layers in the laminate.

TRIMMING AND CUTTING

The best equipment for cutting materials is an abrasive type disc. Diamond impregnated discs generally give a cleaner cut edge and longer disc life. For smaller jobs and for trimming, sabre saws and fine toothed hacksaws are often used. Wherever possible the cutting tool should cut into the face of the corrosion liner, as opposed to away from the face, to minimise excessive chipping of the liner at the cut edge.

For repairs of damaged laminates, all the damaged material should be cut away in preparation for the repair.

MATERIAL PREPARATION

The amount and size of reinforcing material required will be determined by the extent of the damaged area. There are many combinations of wall constructions and loading conditions for equipment, which make it very difficult to provide specific