The Slipline Pipe Terminal Sealing Process and the EGP Technique of sealing polyethylene pipe terminals were discovered when field crews, attempting to seal a Slipline terminal, soaked oakum strips in a liquid prepolymer and packed them around the polyethylene pipe. The resulting seal was effective and so easily accomplished that word of the process quickly spread, and others began to try the technique in a variety of leak sealing situations, such as large diameter storm and sanitary sewer pipe joints, lift holes in manholes and pipes, pick holes in manhole lids, manhole frame and corbel junctions, leaking manhole walls, expansion joints, and abandoned service connections. The ease of application coupled with the superior seal has caused wide-spread acceptance of the technique. The grout saturated oakum material creates a very dense seal which is impervious to water yet able to tolerate joint movement. EGP seals have successfully resisted substantial forces including freeze-thaw and wet-dry cycling. Slipline Pipe Terminal Seals have also successfully resisted vibration, compression, extrusion and thermal expansion.

When PUR is mixed with water, a reaction proceeds through two stages, called Foam (or Expansion) and Cure, which must be understood and controlled to obtain good results. Ambient temperature is the primary variable that affects the expansion and cure times.

When reduced to basics, the process involves three
simple steps:

1. Saturation of oakum with PUR Grouting Compounds.
2. Placement of saturated oakum in the leakage path.
3. Curing of the grout compound in-place.

Though the EGP Technique and Slipline Pipe Terminal Sealing Process can be performed by unskilled labor with a minimum of equipment, some preparation will save time and money.

The primary tools required are:

A. PUR Grouting Compounds - Refer to Material Safety Data Sheets for hazards and safety precautions, available from manufacturer.

B. Plastic bag or pail

C. Rubber gloves

D. Organic vapor respirator

E. Oil-Free Oakum - Meets Federal Specification HH-P-117 (the oakum should not contain oil)

F. Fan (for blowing fresh air into the application area)

G. Blunt instrument (screwdriver, etc.)

The following procedures should be followed:

1. Clean the crack or joint to be sealed of any loose debris and foreign material.

2. Cut the oakum in various sizes to meet the requirements of the cracks and holes.

3. Place the oakum in a heavy-duty plastic bag or pail.

4. Pour PUR into the plastic bag or pail. Pour enough to cover the oakum. Let the oakum soak long enough to get thoroughly saturated with the Chemical Grout. The appropriate protective equipment and ventilation should be used.

5. Take the saturated oakum out of the container and submerse in water for approximately 5-10 seconds. Then hold the oakum out of water until the grout starts to foam (approximately 5 to 10 seconds).

6. Place the oakum into the leaking crack, joint or hole. Use a blunt instrument, such as a screwdriver, to drive the oakum further into the leaking area (joint). The water in the joint will continue to activate the grout that has been absorbed by the oakum.

If dry joints or cracks are being sealed, water should be sprayed into the joint or crack before inserting the activated oakum.

For the Slipline Pipe Terminal Sealing Process, place the PUR saturated strand into the annulus (starting at the bottom). In both processes, the oakum is lightly tamped into place by use of putty knives, wooden dowels or other tools. Water is applied during the tamping process by either a small hose or weed sprayer. Application of water during the tamping causes hydration of the grout compound.

Additional layers of material are built up in the same fashion with each being wetted and tamped in turn until the full gasket thickness is obtained. Only a light spray of water should be used since large volumes of high pressures may wash away the grout before it sets. It is usually desirable to stop the application of material somewhat below the surface so that hydration will not cause the seal to expand into the flow area.

Procedures for expansion joint repairs using PUR grouting compounds will require, in addition to the above, that the joint be free of all debris or old gasket material. Sand blasting may be necessary. Further, the PUR will require curing fore minimum of 12 hours before trimming and cleaning, if the PUR seal has expanded above the surface area. Often it is desirable to fill cracks or joints with a surface seal, which should be a compatible material with elongation capabilities. Contact Avanti for details on a trowelable epoxy gel (paste) for such a surface seal.

During any sealing operation, a large variety of joint spacing will be encountered. Some joints are so thin that a putty knife may be difficult to insert. In other cases, the gap may be so wide that soil is visible outside the joint. Oakum is available in many diameters and it is helpful to have several different sizes on site. For very small cracks, the oakum strips may be separated into fine strands.

I n many cases where narrow gaps are the norm, and a packer is not available, felt strips approximately 1/8" thick and approximately 12" wide may be soaked in the grout compound and applied over the joint. After this material has been allowed to cure in place and bond to the concrete surface, PUR and water may be injected behind the felt and allowed to cure. Containment will be accomplished by the felt which has been bonded to the surface with the grout compound. Plate packers are also effective, particularly on flat surfaces.

Large diameter pipe which has been finished to a smooth surface may sometimes be encountered. In these cases, the oakum and grout should be worked deeply into the joint and "around the corner" in the bell spigot juncture so that a mechanical lock will be created. Bonding to smooth surfaces is also enhanced by "painting" the surface with PUR prior to oakum insertion.

When placing gaskets within concrete using the double dam technique, it is necessary to inject between the seals in order to increase adhesive forces and elongation. This can be accomplished most effectively using PUR with foaming characteristics. It may be injected in a 1 -to-1 ratio by angle drilling through the concrete, or by pushing through the reacted oakum gasket with a grout needle. In a soil pipeline project, where the major objective is to fill voids and encapsulate soil outside the seal, injecting PUR with gel properties in a 1O-to-1 ratio is desirable.

Due to the large number of possible combinations of host pipe and liner, a correspondingly large number of annular space sizes will be encountered Oakum can be arranged in many diameters by separation of one or more strips. For very small spaces, the jute strips may be separated into fine strands.

Very generally, the quantity of oakum required for a single terminal seal may be found by multiplying the host pipe diameter by 0.12. Thus: Oakum (Ibs) = 0.12 X Host Pipe Diameter (Inches)

Undersized liner pipes will, of course, require correspondingly larger quantities. Once the quantity of oakum required has been calculated, the amount of grouting compound needed may be roughly determined as PUR (Ibs) = 0akum (Ibs) X 4.

Fibrotite conforms to Federal Specification HH-P-117 as published in the Federal Standard Stock Catalog, Section IV, Part 5. HH-P-117 was approved by the Director of Procurement on November 5, 1940, for the use of all departments and establishments of the Government Copies are available from the Superintendent of Documents, Washington, D.C. The specification covers twisted jute packing only.

Fibrotite is made from thoroughly carded jute fiber and is practically free from hard, coarse fibers and extraneous matter. It is prepared in rope form with seven strands having a twist of approximately 1.25 turns per foot. It's diameter is approximately 2 inches and weight is approximately 0.4 Ibs. per foot. Strand diameter is approximately ½ inch.

Since only dry jute should be used for EGP applications, Fibrotite contains less than 8% oil by total weight of the packing.

AV-219 Fibrotite is sold and shipped in cardboard containers containing either one (1) 50 lb. coil or 25 two-foot strands. The very loose weave allows rapid absorption of PUR in addition to ease of separation for insertion in small crevices.

The data, information and statements contained herein are believed to be reliable, but are not construed as a warranty or representation for which Avanti International assumes any legal responsibility. Since field conditions vary widely, users must undertake sufficient verification and testing to determine the suitability of any product or process mentioned in this or any other written material from Avanti for their own particular use. NO WARRANTY OF SUITABILITY OR FITNESS FOR A PARTICULAR PURPOSE IS MADE. Nothing in this or any other document from Avanti International is to be taken as permission, inducement or recommendation to practice any patented invention without a license.

©2005 by Avanti International. All rights reserved. Printed in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a data base or retrieval system, without prior explicit written permission from Avanti International.