Applications

 Rebuilding Of Power Blocks

UPS 320 EG '80' Elastomer (TR320)

The following ThistleBond section is concerned with the rebuilding of power blocks and should be read in conjunction with the Technical Data sheets of the following ThistleBond Products: 80 Durometer Elastomer Paste.

COMMON DEFECTS

Mechanical damage to lining material caused by wear and abrasion.

PREPARATION

All work should be carried out in strict accordance with the relevant ThistleBond Technical Data Sheet. Repairs to the power block can be carried out in situ, but it may be necessary to construct a suitable tented work space in order to protect the power block and working engineer from adverse weather conditions. To obtain optimum results, it will be necessary to pre form a suitably rigid template, shaped to give the desired final contour of the power block.

SURFACE PREPARATION

Thoroughly fry the repair area and cut away all loosely adhered material using a sharp knife. Undercut existing rubber covering at the extremity of the repair area. Roughen the exposed power block carcass using an angular grinder, fitted with a cutting wheel, or a similar tool capable of roughening the surface. The surrounding rubber coating should also be roughened using a roughing brush to produce a woolly surface. If an entire new coating is to be applied, then the metallic carcass of the power block should be roughed by grit blasting to Swedish Standard Sa2½ ensuring a minimum profile of 75 microns, using an angular abrasive.

PRIMING SYSTEM

Apply the ThistleBond Primer supplied with the 80 Durometer Elastomer product in a thin film using a stiff bristled brush to the entire prepared area. All surfaces to which the material is to bond to must be treated.

APPLICATION TECHNIQUE

Mix the selected ThistleBond product in accordance with the Technical Data Sheet. Using a short Bristled Brush or the flexible applicator provided, apply a thin layer of product to wet out the prepared surface. Ensure that this material is pushed well into the prepared profile. Using a suitably shaped rigid template, apply further product whilst the power block is slowly rotating, until the original profile has been restored.

TECHNICAL SUMMARY

PRODUCT                                                  ABRASION            WORKING             FULL CURE

                                                                  RESISTANCE            LIFE (20°C)            (20°C)

80 DUROMETER

ELASTOMER PASTE                               EXCELLENT            15 MINUTES            72 HOURS

Rebuild of Eroded & Corroded Pump

Housings

Common Defects

Pitting and Scarring on external surfaces produced by prolonged periods of exposure to highly abrasive products, leading to a reduction in performance and efficiency and ultimately holes in the outer surface of the pump housing. Without preventative maintenance or repair this can lead to scrapping of components.

Preparation

All work should be carried out in strict accordance with the relevant ThistleBond Technical Data Sheet. The product selection and application techniques should be based on the nature of the repair and the product being pumped.

Surface Preparation

There two types of repair that can be carried out by the ThistleBond product range.

If the pump housing cannot be taken out of service, but the system pressure can be turned off for 1-4 hours, thus stopping any product passing through the pump. The outer surface of the pump housing should be abraded using a grinding disc to remove any surface rust or surface contaminants. The area to be repaired should then be cleaned using UPS TAC 883 Universal Cleaner (TAC883).

If the pump can be taken out of service, then blast clean the damaged area to Swedish Std Sa2½ ensuring a profile of 75 microns minimum using an angular grit. This method of surface preparation will ensure a longer lasting repair. After blasting, all damaged areas must be cleaned using UPS TAC 883 Universal Cleaner (TAC883).

Application Technique

In situ repair and out of service repair– Using the chosen ThistleBond product (UPS 105 EG Metal Repair Paste (TR105), UPS 115 XL Extended Life Metal (TR115), UPS 19065 RG Rapid Grade Metal (TR19065), UPS 19060 SG Stick Grade Metal (TR19060) or UPS 200 EG Ceramic Repair Paste (TR200), apply the material, using the applicator provided, in to the hole or crack. Ensure that the product applied has been pushed sufficiently into the surface of the pump housing and covers al of the effected area. Once this has been achieved apply the ThistleBond material onto the surrounding area to the repair, approximately 2” in all directions. The product should then be left undisturbed to fully cure before the equipment is returned to service. 

The Casting of Cutlass Bearings

Common Defects

A). Damage due to dry running.

B). Loss of clearances due to damage from abrasive particles.

C). Damage caused by shaft misalignment or vibration.

Preparation

All work should be carried out in strict accordance with the relevant ThistleBond Technical Data Sheet. Product selection and application should be based on the nature of the damage and the amount of time available for the repair to be carried out.

Surface Preparation

A suitable mould must be manufactured, this can be done by using one of the two techniques outlined below:

a). Produce a centralising jig for the existing outer sleeve of the bearing and machine a suitable metal insert to the configuration of the internal dimensions of the bearing. This should then be centralised within the outer sleeve to produce a mould.

b). Alternatively, UPS 205 FG Fluid Grade Ceramic (TR205) and UPS 235 BG Urethane Ceramic Fluid (TR235) can be used to cast an inner mould. This can be done by coating the internal surface of a new bearing/ bush with two coats of UPS TAC 872 Release Agenet. Once allowed to dry, the bearing can be centralised in a jig and one of the UPS 205 FG Fluid Grade Ceramic (TR205) can be poured in a thin stream to fill the centre cavity. When the material has cured the original bearing may be removed leaving the cured core adhered and centralised in the jig.

Produce a new outer sleeve from suitable materials or alternatively, remove all existing rubber from the existing sleeve and prepare the internal surfaces by grit blasting to Swedish Standard SA 21/2 ensuring a minimum profile of 75 microns, using an angular abrasive. Clean the component thoroughly with ThistleBond Universal Cleaners and treat the surface of the former with a minimum of two coats of ThistleBond Release Agent and allow to dry.

Priming System

Apply the UPS 075 Elastomeric Primer supplied with the UPS 300 FG '60' Durometer Fluid Grade Elastomer  or UPS 315 FG '80' Durometer Fluid Grade Elastomer product in a thin film using a stiff bristled brush to the entire prepared area. All surfaces to which the material is to bond to must be treated.

Application Technique

Mix the selected ThistleBond product in accordance with the Technical Data Sheet. Using a short Bristled Brush, wet out the internal surfaces of the former and the internal diameter of the outer sleeve. Position the former and outer sleeve into the mould and centralise. Immediately pour the remainder of the pre mixed material in a thin stream in order to prevent excessive air entrapment. Continue to pour until the material fills the mould to the desired level and allow to cure in accordance with the data sheet, after which, the bearing can be removed and any excess material removed using a sharp knife.