Grout Application & Technical Specification


Reference Documents:  
3CS02001 Grouting of Equipment and Structures
4ACS-640106 Grouting of Equipment and Structural Steel
M13 Grouting of Equipment and Structures


  1. Planning
    1. Make sure the contractor has and understands all the applicable specifications, and has selected approved grouting materials. Consult 4ACS-640106 for current approved grouting materials, or check with the home office.
    2. A meeting needs to take place between the grouting contractor, the grout manufacturer representative and the Air Products representative to provide instruction on correct grout installation, and to talk about the grouting process on site. The record of the meeting shall be kept in the QA/QC file.
    3. The contractor should create a grout schedule, including dates of grouting, location, type, and amounts needed to better define their work. Check the schedule to make sure that the proper grout type is being used for each piece of equipment or support.  Appendix “A” may provide some guidance with this, but the contract documents will control.
    4. Make sure that the mechanical contractor has checked all of the foundations for elevation, size, and anchor bolt location. The mechanical contractor shall sign a letter regarding the correctness of the foundations, prior to starting. This requirement is listed in 4WCE-60001.  The nominal thickness of the grout must be in accordance with the grout schedule. Machinery Applications approval must be obtained when thickness of grout is outside the given tolerance.
    5. Verify that the concrete has cured for 28-days. If time constraints do not allow for this, the concrete should be allowed to cure for a minimum of 7 days, and has reached a minimum compressive strength of 3000 psi.
    6. Grout is generally placed under all load-bearing base members, including skid support members on the inside of compressor, pump, or cold box skids. Some equipment and compressors, generally Sulzer machines, may also require annular space be grouted within the structural or machine frame. Clarify with the designer if the extent of grouting is not perfectly clear.
    7. Some equipment needs minimum spacing between equipment parts and the level of grout for equipment cooling. Check the drawings for particulars.
    8. For epoxy grout, make sure that the workers all have the proper personal protective equipment, the area is well ventilated, and no smoking is allowed.
    9. Epoxy grout must be used in all situations where resiliency to high impact, dynamic loading is needed, or bearing pressures require the higher strength. If there is temperature build-up that is greater than 120F, high temperature epoxy shall be used.
    10. Epoxy grout must be used for the grout around column cans or field built cold boxes where the bottom of the purged enclosure is the concrete foundation. The epoxy grout provides a proper seal around the base preventing purge gas migration to the exterior.
    11. Where grout is used to fill skids or motor bases to prevent water becoming trapped next to the supports, the grout supporting the frame needs to be installed first and allowed to cure. Appendix B shows a typical drawing of this type of installation.
    12. Ladders, stairways, transformers, and electrical panels do not need to be grouted.
    13. Storage time for non-shrink grout or Portland cement must be limited to 6 months. For epoxy grout, check the manufacturer’s recommendations.  In all cases reject materials that appear spoiled and have the contractor supply new materials.
  2. Special Concerns With Anchor Bolts
    1. Make sure that the foundations where the anchor bolt pockets are to be grouted and the foundations with pockets that do not get grouted are clearly identified. Not all anchor bolt pockets require filling of annular space with grout.  Verify drawings and grout schedules to determine specific grout requirements for anchor bolts.
    2. Anchor bolt sleeves must be clean, dry, and protected from the entry of foreign material regardless if anchor bolt sleeve annular space is to be grouted.
    3. When annular space anchor bolt sleeves are not to be grouted they shall be sealed to prevent grout entry. Anchor bolt sleeves that are not to be grouted might use another material, such as sand, to be installed around the anchor bolts.  Verify drawings and anchor bolt schedules to determine correct installation.
    4. Cover the exposed area of the anchor bolt and jack bolt threads prior to grouting to prevent bounding. Avoid getting grout inside the jack bolt sleeves.
    5. Anchor bolts shall not be tightened until the grout under the base members has completely cured and has reached design strength.
    6. In some cases, grout may be needed in the bolt sleeve after bolt torquing is complete. Make sure the bolt is properly tightened before allowing those sleeves to be filled.  This is required in cases where lateral strength of the bolts is necessary.




  1. Surface Preparation
    1. Equipment base plates on cementitious grout shall be completely clean of loose paint, rust, dirt, and oil. When using epoxy grout and base plates are coated with epoxy paints in good condition, only remove oil, dirt, and grease is necessary.
    2. A minimum of 50% aggregate must be exposed using a hand held chipping hammer. Also remove any weak, cracked, dirty, or oil soaked concrete.  The key is to provide a clean, rough texture for grout to bond with the concrete.
    3. The thickness of the grout required must be in accordance with the design drawings. If none are shown, refer to the table in Appendix A, which lists the nominal grout thickness for common pieces of equipment encountered on site.
    4. Contact the machinery engineer when the thickness of grout will be more than ¼” outside of the designed or nominal thickness. Do not allow that equipment to be grouted until discrepancy has been resolved.  Consult grout manufacturer’s representative for recommended corrective actions.
    5. Exposed reinforcing steel shall be cleaned to be rust and oil.
    6. If shims or wedges need to be removed after grouting, have contractor blocks out the areas around them to ease removal. Jack bolts are recommended instead of shims and wedges.
    7. Clean all surfaces that will be grouted with high pressure oil-free air. High-pressure water is an alternative when non-shrink or sand-cement grout is used.
    8. For epoxy grout, the grout surfaces must be dry and oil free prior to placement. Foundation surfaces are not to be wetted when using epoxy grout.
    9. For sand cement and non-shrink grout, the grout area shall be soaked with water 24 hours before placement to saturate the base concrete. All standing water must be removed prior to placing grout.  A wet -type “shop-vac” is useful in removing standing water.
  2. Forming
    1. All forms need to be set so that the grout is introduced from one side of the foundation. At least 4” of clearance between the form and the equipment base external edge, and 12” above the finished grout level is recommended.
    2. On all other sides, a clearance of at least 2” is required between the base edge and the form. At least 4” of form height above the finished grout level is needed.
    3. The grout limits should extend from the edge of the equipment base outward to a distance that is at least equal to the thickness of the grout, but not more than twice that.
    4. All forms shall be clean and treated to prevent bonding with cured grout.
    5. Epoxy grout forms should use two coats of paste wax or a plastic sheet.
    6. Sand-cement and non-shrink grout forms should use a non-staining form release oil or soft paste wax on wood or metal forms. The forms should be thoroughly wet and maintained wet until the grout pour.
    7. Liquid wax is not permitted for sealing forms. Use liquid wax that is spills on the grout surface during installation will prevent bond between the grout and the concrete.
    8. All forms should be properly caulked and sealed to prevent leaks and therefore loss of head pressure during the grouting process, to prevent undercutting of the grout.
    9. Check the base plates or members for areas that might hold air pockets during the grouting operation. Provide vent holes in those locations.
    10. Request guidance from the machinery engineer or vendor representative for placement of dams beneath the compressor or motor to isolate areas requiring grout. Area of grout may be minimized so not to interfere with the machine cooling.
    11. Install expansion joints in large grout areas as per the manufactures recommendations and in specification 4ACS-640106. Appropriate expansion materials are specified in 4ACS-640106.
  3. Grout Placement
    1. Foundation and base plate temperatures shall be 35°F to 75°F for cementitious grouts and 40°F to 90°F for epoxy grouts.
    2. In extremely hot weather, the grouted base plate shall be cooled after the grout placement by covering with wet burlap and cooling with soaker hoses. In cold weather, the grouted base plate shall be heated for 24 hours to keep the temperature within the above limits.
    3. Make sure that the contractor has established a contingency plan in case the grout job cannot be completed. The workers should know how to knock out forms and washout the area under the plates without causing trouble to other areas.
    4. Vibration from running the equipment being grouted or neighboring equipment might affect the grout being installed by causing settlement and segregation. All equipment that will affect the grout due to vibration needs to be shut down until grout curing is complete.
    5. Sand-cement proportioning needs to be done as specified in 4ACS-640106. Other grout types need to be prepared according to the manufacturer’s instructions.
    6. Sand-cement and non-shrink grout batches should be no larger than what can be placed in 45 minutes. Epoxy grout has a maximum working time of 120 minutes.  It should be placed within 30 minutes of mixing it.
    7. Grout shall be mixed in areas as close to the grout placement.
    8. Grout shall be placed continuously so as to avoid overworking and segregation.
    9. Grout that has stiffened shall be discarded and a new batch prepared. Do not permit the contractor to add water and remix.
    10. Trapping air under the base plates has to be avoided. Pouring grout from one side only, pumping in grout, rodding with metal straps, and air relief holes should help prevent this.
    11. A grout headbox, where the level of grout inside is above the level of the grout around the foundation shall be used so that the hydrostatic pressure of the grout is maintained.
    12. Grout test cubes shall be taken and tested in accordance with specification 640.140. Have contractor schedule independent testing laboratory for this work.
  4. Finishing and Curing
    1. During the curing process the equipment grouted shall not be operated nor have lateral forces imparted on the bases. Excessive vibrations will damage the grout.
    2. Excess grout material on the foundation needs to be removed.
    3. Grout shoulders can be finished when penetration by a pointed mason’s trowel becomes difficult. The main objective is to avoid cutting back shoulders while grout is still soft enough to separate from the equipment-bearing surface.
    4. Epoxy grout do not requiring finishing. Edges shall be formed with chamfer strips.
    5. After finishing work is complete, cementitious grout shall be protected to maintain the moisture content and temperature control until the compressive strength of 4,000 psi is attained. Temperatures between 35-75 degrees must be maintained for 24 hours
    6. Protection for cementitious grout should be PVC sheets or canvas, burlap, or other adsorbent materials saturated with water. Water should be added when the grout under the protective materials starts to dry out. Cementitious grout shall be kept moist for a minimum of 3 days after pouring.
    7. Manufacturer’s recommendations shall be used for epoxy grout curing requirements. Do not moist cure epoxy grout.
    8. All surfaces of grout exposed to weather or around oxygen compressors shall be coated with a flexible oil-resistant sealant to prevent water and oil from seeping under the base.
    9. Shims, wedges, and jackscrews that need to be removed shall only be removed after the grout is cured and checked for proper strength. Voids in the grout left by the removal of wedges and shim packs shall be filled with similar grout material.
  5. QC Documentation
    1. Copy of the grout representative meeting
    2. Sign off on foundation correctness by the contractor
    3. Copy of the grout schedule
    4. Cut sheets of grout used
    5. Grout test cube compressive strength results



Appendix A


Grout Type and Thickness












when required

     Compressors   ·   50 mm (2.0 in)
     Skid Frames and Castings   · Full Depth 40 mm (1.5 in)
     In-line Snubbers   ·   40 mm (1.5 in)
     Pumps   ·   40 mm (1.5 in)
     Motors (Drives)   ·   50 mm (2.0 in)
     Centrifugal Compressor ·(2)     25 mm (1.0 in)
     Skid Frames and Castings ·(2)   Full Depth 25 mm (1.0 in)
     Turbines   ·   50 mm (2.0 in)
     Motors w/Sole Plates/Rails   ·   50 mm (2.0 in)
     Motors w/o Sole Plates/Rails ·(2)     25 mm (1.0 in)
     Heat Exchangers ·     25 mm (1.0 in)
     Truck Scales ·     25 mm (1.0 in)
     Lube Oil Consoles ·     25 mm (1.0 in)
     Shop-Assembled Cold Boxes ·     40 mm (1.5 in)
     Field-Erected Cold Boxes   ·   40 mm (1.5 in)
     Insulation Containment Can   ·   40 mm (1.5 in)
     Building Columns (if required) ·     25 mm (1.0 in)
     Pipe Rack Column ·     25 mm (1.0 in)
     Miscellaneous Equipment Supports ·     25 mm (1.0 in)
     Miscellaneous Pipe Supports ·     25 mm (1.0 in)
     Skid Frames ·   Full Depth 25 mm (1.0 in)



(1)  Projects performed utilizing M13 may substitute sand/cement grout for cement-based non-shrink grout if appropriate.

(2)  Epoxy grout may be substituted at the discretion of the machinery engineer when the complexities of the equipment base and grout details make the effective placement of cement-based non-shrink grout very difficult.


Appendix B


Primary and Secondary Grout Pours




Other Info

Document Category Engineering
Document Target Users

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