By A Web Design

GMA GarnetTM blast cleaning abrasives are well suited to most fields of surface preparation industry, with or without subsequent coatings in particular:

  • Bridge and weir lock.
  • Building and structural steel.
  • Construction and maintenance of chemical plants, nuclear and fossil power stations, gas and sewerage plants, desalination and industrial plants.
  • Construction and maintenance of containers and tanks, tank trucks and rail tanks, wagons and coaches.
  • Non-ferrous surfaces and turbine blades (special mesh).
  • Oil and petrochemical maintenance in refineries and storage tanks including on-shore and off-shore installations.
  • Shipyards, new building, conversion and repair including antimagnetic and other special steels as well as aluminium super structures and aluminium and fibreglass hulls.
  • Stainless Steel.
  • Stone building facades and monuments.

GMA GarnetTM provides optimum blasting efficiency and economy if correctly applied. Here are some guidelines:

1. Ensure the nozzle air pressure is 95-100psi (measured at the nozzle). Note: for every 1psi under 100psi, efficiency is reduced by 1.5%, i.e. at 70psi you are blasting at 55% efficiency.

2. Check nozzle pressure frequently with a hypodermic needle gauge

3. Check nozzle frequently for wear and replace when worn to ensure optimum productivity is maintained.

4. Check all blast pot fittings, hoses and hose couplings, both air and air/abrasive and repair anything that are faulty immediately. Any air leak will cause a loss in pressure at the nozzle.

5. Use an efficient moisture removal system to prevent pressure drop.

6. Fit an abrasive valve that can accurately meter the abrasive flow to ensure correct air/abrasive mix in the blast hose as accurate abrasive metering is very important.

7. Ensure all blast pots are supplied by an air hose that has a minimum id of 40mm (1 1/2") preferably 50mm (2"). This hose must be fitted with non-restrictive coupling fittings.

8. The air piping on your blast pot must be a minimum of 32mm id (1 1/4"). Be sure that full port ball valves are used on the choke valve. Do not use reduced port valves anywhere in the system as a pressure drop will occur because of restricted air flow through the ball valve.

Optimum Setup

GMA Garnet offers a choice of grades to match any focusing tube and orifice for any given cutting application. 
GMA Garnet™ 80 Mesh: The most popular waterjet cutting abrasive grade used worldwide delivers the optimum balance of cutting speed and precision edge. 
GMA Garnet™ 50 or 60 Mesh: Suitable for high speed waterjet cutting, it can in some cases deliver up to a 30% increase in cutting speed but at the expense of a reduced precision edge. 
GMA Garnet™ 120 Mesh: For high precision and minimum tolerance edge cutting requirements.
The table states the correct combinations of GMA Garnet™ grades, focusing tube and orifice dimensions to suit your particular waterjet cutting requirements.

  GMA Garnet Grade Focusing Tube Orifice
 Industry Standard Configuration80 mesh
300-150 micron
.030 - .040"
.762 - 1.02mm
.010 - .014"
.330 - .356mm
 High Speed Cutting60 mesh
400-200 micron
50 mesh
600-200 micron
.014 - .015"
.356 - .381mm
.016 - .018"
.407 - .457mm
 Precision Edge80 mesh
300-150 micron
.030 - .040"
.762 - 1.02mm
.010 - .014"
.330 - .356mm
 High Precision Edge120 mesh
200-100 micron
.020 - .030"
.508 - .762mm
.007 - .010"
.178 - .330mm
 Fine Precision Edge200 mesh
50-150 micron
.020 - .030"
.508 - .762mm
.007 - .010"
.178 - .330mm