DESCRIPTION
UCAR GR37™ Grout is a two-part carbonaceous grout with expanding flake graphite. This expansion occurs at approximately 200°C while exerting a low volume expansion pressure of less than 1 psi (7 kPa). This permits the grout to expand for a tight fit around under hearth cooling pipes and similar structures. GR37™ Grout has been used to reestablish contact between carbon refractory and cooling members, as well as stop gas leaks in blast furnace applications.

APPLICATIONS
GR-37 Grout is used to re-establish contact between refractories and cooling members, as well as to stop gas leaks in blast furnace applications. Examples are spray cooled or panel cooled boshes and hearth jackets, which require intimate contact between refractories and the cooled element for proper heat transfer and long life. Often, as campaign lives grow longer and longer, differential movement between the steel jackets or staves and the refractories can result in separation between the jacket or staves and the refractories. This separation not only interrupts heat transfer from the refractories to the jacket or stave, but also permits high temperature gasses to circulate in the annulus formed. This gas channeling, if unabated, can result in hot spots and refractory loss. GR-37 Grout can be pressure grouted into the annulus formed between refractories and the cooled element to stop gas channeling and re-establish thermal contact to improve cooling of the refractories and extend life.
 
Another application of GR-37 Grout is to re-establish contact with refractories when it is necessary to remove damaged shell plate which exposes refractories. When the replacement patch plate is reinstalled, weldment shrinkage will cause the patch to "pull-away" from the refractories. GR-37 Grout can then be pressure grouted into this cavity to re-establish thermal contact. This is also useful when making taphole repairs.
 
GR-37 Grout can also be useful for reducing or eliminating gas leakage or blowing around tuyere coolers, copper cooling plates, gaps between tuyere jackets or hearth jackets and staves or any other such leak situation, until permanent repairs or replacement are possible.



 
PACKAGING
The ingredients for the preparation of GR-37 Grout are supplied in individual containers which show the contents and are supplied in standard 50.3 Kg (111-pound) and 79.4 Kg (175-pound) package units.
 
STORAGE
The unmixed ingredients for GR-37 Grout will not deteriorate if kept covered and stored in a cool, dry place.
 
PREPARATION OF GROUT
Standard packaging of the 50.3 Kg (111-pound) unit provides for one 21.3 Kg (47-pound) container of liquid to be mixed with one 29.0 Kg (64-pound) companion drum of powder. For the 79.4 Kg (175pound) unit, mix one container of liquid with two containers of powder. If a smaller quantity is desired, use 100 parts by weight of powder to 35.3 parts by weight of liquid. The liquid should be thoroughly stirred before removing from the container.
 
The viscosity of the grout is determined by considering the distance between grouting connections, anticipated annulus to be filled, type and pressure capability of the pumping apparatus, hose size and length, etc. Therefore, it is impossible to specify a product mix ratio that is suitable for every situation.
 
In general, if small annular spaces (gaps) are anticipated or if grout connections are spaced more than 1.8m (6 ft.) apart, thinner grout viscosity may be required. However, the thicker the grout, the more solids are present, therefore the better the resulting heat transfer and joint filling capability. So the goal should be to make the grout as thick as can be effectively pumped and injected. This may require trial and error at the site. Some on-site "experimentation" may be required to properly pump the material or to get the grout to flow properly between injection nozzles. It is recommended to start with the "Trowelable" mix described below. If this mix proves too thick for the annular space to be filled effectively, more liquid can be added to "thin" the grout to make it "Pumpable".
 
1. TROWELABLE: Mix two boxes of powder (58.1 Kg/128 pounds) with one can of liquid (21.3 Kg/47 pounds). This mixture can also be pumped. This provides approximately 57 liters (15 gal.) of grout.
PUMPABLE: Mix four boxes of powder (116.2 Kg/256 pounds) with four cans of liquid (85.4 Kg/188 pounds). This provides approximately 133 liters (35 gal.) of grout. Based on the application conditions and available equipment, the liquid level can be varied from 3 cans to 5 cans to obtain the required consistency.
 
2. The ingredients should be mixed in either a cement (paddle) mixer or in a metal drum using electric or pneumatic portable mixers. Because of the fineness of the dry powder portion of the grout, agglomerates may be found occasionally when stored under high humidity conditions or when containers have been punctured. In such cases, the powder should be sifted through a screen about the mesh size of a window screen prior to mixing.
3. During cold weather, the grout will mix and apply better if both powder and liquid have been pre-warmed to approximately 20°C (70°F). After mixing the warmed components, place grout in metal container and hold at 20°C (70°F) in a water bath.
 
4. To start mixing, pour approximately 1/4 can of liquid into a clean mixing container. Slowly pour and blend 1/2 bag of powder and then add 1/4 can of liquid. Within five minutes, this portion should be completely mixed. Add the remaining 1/2 can of liquid and 1/2 box of powder. Allow 5-10 minutes to complete mixing. If using steel drums, the mixing should be stopped periodically and a shovel or other tool used to scrape any loose, dry powder which may accumulate on the drum sides.
 
5. Add the remaining containers of powder and liquid to achieve the desired grout consistency for either troweling or pumping. After all ingredients are added, continue mixing for additional 15-20 minutes or until it is completely mixed with no visible lumps or dry powder.
 
6. Once mixed, the grout should be used within the following time periods depending on ambient temperature:
      Temperature Time Period 20°C (70°F) 15 Days 40°C (100°F) 3 Days
Cover grout and store in cool (20°C/70°F or less if possible) place when not in use. Before reusing, warm the stored grout to approximately 20°C (70°F) and re-mix or stir to uniform consistency.
 
7. Mixers, tools, etc. can be cleaned with small amounts of the liquid component followed by hot soapy water. Do Not use the liquid component to clean hands, clothes, or plastic.
 
PREPARATION FOR GROUTING
Whenever pressure grouting is anticipated, the actual grouting (injection) procedure must be conducted with process blast pressure totally "off-wind". Preferably, backdrafting can be initiated to generate a negative pressure (slight vacuum) in the process vessel.
 
Prior to actual grouting, it is advisable to locate or install a sufficient number of injection nozzle connections, taking care to observe proper procedures for their installation.  It is suggested that if half couplings or similar connections are utilized, they consist of 30mm (1-1/4 in.) pipe size or larger, 42 mPa (6000 psi), forged steel fittings. All connections which require welding, drilling or cutting of the process vessel, must be done in strict accordance with the ASME Pressure Vessel Code or similar applicable code.  Any valves, fittings, caps, elbows, etc., must be forged or cast steel. No brass or cast iron shall be used.  All pipe shall be Schedule 80 or greater, seamless steel.
 
The number of connections for grouting can vary greatly depending upon the thickness of the annulus to be filled (gap between shell and brick). Generally, a very small annulus, say 2mm (1/16 in.) will require a thinner viscosity grout and more connections to properly fill than a 5mm (3/16 in.) gap, which would require a thicker viscosity grout and easier "flowability" in the annulus.  Often, the physical configuration of the steel jacket or spacing of cooling elements dictate the possible locations and number of grout injection nozzles.
 
As a general rule, grouting nozzle connections spaced 1.2 to 1.8m (4-6 ft.) apart give successful results. When large vertical areas are to be grouted, nozzles should be placed such that grouting can progress upwards, from the lowest nozzles to the highest, taking care to maintain the 1.2 - 1.8m (4-6 ft.) spacing, both vertically and horizontally.  This may require two, three or even four levels of nozzles. However, if this number of nozzles is impractical or impossible due to shell configuration restrictions, fewer nozzles will mean higher grouting pressures and/or thinner viscosity grout, to provide the required coverage.
 
Generally, grouting nozzles or connections can only be used once, unless it is possible to drill-out and clean the previously solidified grout. If complex delivery piping is used to inject grout into inaccessible areas, this piping will completely fill with solidified grout and will not be reusable.  Care should be taken, that any grouting nozzles, connections and piping configurations which contain GR37 grout shall never be allowed to come in contact with open flames or extreme radiant heat. Appropriate heat shielding and insulation must be provided in these cases.
 
PROCEDURE FOR USE
When used as a pumpable grout, the following general procedure is recommended but may require some minor adjustments depending on available equipment.
 
Pre-lubricate the supply hose by pumping two cans of liquid component through the system.  This liquid should be pumped into a clean receptacle for re-use.
 
Typical pumping conditions:

• Pump Outlet Pressure: approximately 2400-3100 kPa (350-450 psi).
• Pressure at Valve: 500-600 kPa (75-100 psi) maximum. ·
• Valve Size: Apollo 1-1/4" I.D. (31.75mm) or equivalent.

 
Typically, 34 liters (90 gallons) can be pumped using the above conditions in about one hour.
The liquid level in the grout may have to be adjusted to better match the equipment and application conditions. However, it should not be less than or greater than the mix ratios described earlier for the trowelable or pumpable grout.
 
Grouting should commence at the lowest connections and progress at each lowest connection until grout appears at the next highest connections. At this point, grouting shall then begin at these connections, until grout appears at the next highest connections, etc. Continue this process until the entire area is grouted and all uppermost connections show evidence of grout fill.  All connections should be suitably closed by steel valves and plugs or pipe caps. No brass or iron valves or fittings should be used. All valves should be plugged or capped. Never permit a grouting connection to be terminated with an uncapped or unplugged (open-ended) valve.
 
After all grouting is completed and grout connections properly sealed, the process vessel may be pressurized and operated. Generally, residual heat in refractory linings will provide sufficient temperature above 200°C (390°F) to cause the grout to expand and set-up long before the vessel is brought back on line. However, if a very thick layer of grout, say greater than 5mm (3/16 in.) thick, is required next to a cooled element like a spray cooled shell, the total expansion, curing and solidification may require additional time to be completed. The incorporation of thermocouples in the cold face of the lining at a depth of 25mm (1 in.) can help monitor the refractory temperature versus time as the grouted annulus expands and "cures". Experience has shown that cold face refractory temperatures can drop 260°C (500°F) or more after grouting, once the heat transfer is re-established by grouting with GR-37.
 
If a very large annulus (greater than 5mm - 3/16 in.) is to be grouted, additional solids such as UCAR SMARTRAM® Grade RP-20 Expanding Graphite Ram may have to be added to the mix. It is generally better in these situations, which often result during repair situations when steel shell plates are removed and replaced, to utilize UCAR's expanding graphite ramming material, "SMARTRAM® Grade RP-20". Please consult UCAR for additional information if such a situation is expected.
 
When necessary to fill or seal thermocouple holes, probe holes, etc. 15-50mm (3/4 - 2" diameter) in a hot furnace or application, you should use graphite rod or sheath without grout. Use of grout creates potential for vapor pressure build up and blow back.
 
PRECAUTIONS FOR USE IN A HOT FURNACE APPLICATION
This product is designed to be pumped into a hot operating furnace which has been temporarily shut down to grout and reestablish contact between the refractory and the cooling members.  Heat above 200°C (350°F) is needed to cause the expanding graphite to expand and complete the cure or thermally set the grout.
 
At temperatures above 70°C (160°F) furfuryl alcohol begins to vaporize and flashoff. Always be certain that grouting practices allow for the escape of furfuryl alcohol vapors. DO NOT pump grout into closed, heated areas. Pressure blowback may occur.
 
DO NOT expose personnel to furfuryl alcohol fumes. Wear respiratory protection if appropriate. Consult UCAR MSDS 4250 for precautions.