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Common Questions

Gasket Selection and Sizing

How does HK’s engineering department determine which gasket should be used for my application?


Simply put, it’s basic math. Our engineers make sure that there is enough “stretch” on the gasket to keep it in place on the spigot during the homing process, and the gasket cross section is sufficient to provide adequate force, fill the space provided by the joint design and meet ASTM requirements. And, all of this must be done without putting too much rubber in the joint which could lead to an inability to home the pipe or manhole sections properly or to break the bell.

Does a single offset joint with a profile gasket meet the requirements of ASTM C361?


Yes, as an alternative joint design, a single off-set joint in combination with a profile gasket can be used as a substitute for o-ring gaskets and confined o-ring joints, but it should be approved by the owner prior to manufacture and proven that the test pipe complies with the specification. Additionally, the gaskets must be manufactured from a material that can meet the requirements for ASTM C1619, Class A low pressure piping applications. Also, job site conditions must be evaluated by HK engineers to ensure a proper level of safety in the performance of a profile gasket and single off-set joint. Hamilton Kent is able to supply documentation of such calculations and information needed to meet the project requirements.

Gasket and Pipe Installation

Sometimes I hear a popping sound when homing Tylox® SuperSeal™ gaskets. Is this normal? Will it affect the performance of the gasket?


While it’s rare, during the splicing process or while injecting the silicone lubricant into the rolling tube, sometimes extra air becomes trapped in the tube of the SuperSeal™ gasket. During the homing process, the rolling tube gets squeezed and can rupture (causing the popping sound) if too much air is in the tube. This part of the gasket is not responsible for any of the sealing properties of the gasket (the “body” of the gasket creates the seal). As such, this will have no effect on the performance of the gasket.

I’m installing pipe in very cold conditions. Do I need to handle the gaskets any differently?


As rubber gets cold, its durometer increases (in other words, it becomes harder). While standard compound gaskets will remain in spec even in the coldest temperatures, the harder a gasket becomes, the more the insertion force of the pipe will increase. So, if you can keep the gaskets in a warm environment just prior to installation this will make the homing process easier to perform.

What suggestions can you provide on installing gasketed pipe?


Ensure the trench is very level and firm. Clear the bell of the previously laid pipe of any debris. If you are using a profile gasket, install it on the spigot and equalize, and then lubricate the bell and the spigot-facing side of the gasket thoroughly. For the SuperSeal™, no equalization is required and no lubrication should ever be used. Bring the pipe into the trench level and place it so the spigot is right next to the bell of the previously laid pipe. Check that the gasket is still in position against the step of the joint. After ensuring proper alignment with the adjacent pipe section, push the pipe section fully home using an approved means provided by the pipe supplier. Check the alignment of the pipe with a laser and make any final adjustments before moving to the next pipe section. Once homed, the pipe should not be lifted or pressed down in order to meet the proper grade. If grade adjustments must be made, the pipe section should be removed, the base material adjusted and then the pipe replaced and homed. If you are installing elliptical or arch pipe, pre-lubricated gaskets are suggested. Follow these same steps when installing pre-lubricated gaskets.

Can we – or should we – use pipe lubricant with the Tylox® SuperSeal™ gasket?


No. Lubricant should never be used with this gasket as it is already pre-lubricated within the rolling tube. If external lube is used, the bell may not catch the rolling tube when the joint is homed, preventing the body of the gasket from being pulled tightly against the single offset step. This may limit the sealing capacity of the gasket. If you’re having trouble homing pipe, manhole risers or box culvert sections with this gasket, you should check the dimensions of the joints as well as the joint tooling. As tooling wears, it makes the joint tighter, leaving less space for the gasket. Sometimes difficulty homing pieces can be an indication of tooling that is out of tolerance.

Gasket/Pipe Testing

I’m having trouble passing hydrostatic tests. Do I need a larger gasket?


While it’s easy to find fault in the gasket when a joint leaks, it is only one variable among many that can lead to joint leakage. Seek answers to these questions as well:

  • Are there bugholes or voids in the bell or spigot where the gasket will be sealing?
  • Is the step (single offset design) properly formed around the full circumference of the joint?
  • Has worn or damaged tooling caused the finished product to become out of round or out of tolerance?

These are some of the factors that that can lead to joint leakage. Please contact your HK representative to discuss. Our team of territory managers and engineers can help you with these issues.

How can I get joint tolerance and Go-No-Go gauge drawings?


The Hamilton Kent engineering department provides these drawings upon request for our customers. Please contact your territory manager to start the process.

Gasketed Box Culverts

My project requires box culvert gaskets to be installed before shipping. How long can I leave them exposed to the elements before the gasket quality is compromised?


While we never recommend leaving gaskets exposed to the elements for an extended period of time, HK’s box culvert gaskets are made from a UV-resistant rubber (EPDM). Exposure to the elements should be OK for a longer period of time, but will vary depending on the climate. Exposure times will be shorter in extreme heat climates and longer in colder climates. Generally, six to nine months of storage of box culvert sections will not adversely affect the installed gaskets. Gaskets should always be inspected prior to shipping to ensure they are still properly positioned and the bottom section is well adhered to the spigot. For your application, please contact an HK representative for more information.

What is the gap tolerance on the inside of a gasketed box culvert when sections are fully homed?


Hamilton Kent considers a ½” maximum gap on the inside of the culvert to be acceptable per applicable testing procedures and ASTM standards.

Can or should we use adhesive, sealant or lubricants along with the TSS gaskets on box culvert sections?


Yes, the gaskets will need to be glued to each structure’s spigot end of the joint per the instructions in the product literature. Hamilton Kent recommends using our Tylox® Adhesive for this application. As for butyl sealants, these can be used in conjunction with a gasket, however Hamilton Kent does not recommend this practice without first consulting with one of our engineers. Correct placement of sealant in a joint is critical to be effective and to not inhibit a gasket’s ability to function. Lubricants should never be used on joints with the TSS pre-lubed gasket.


What physical differences will I notice between regular rubber gaskets and oil-resistant gaskets?


The oil-resistant gaskets generally will feel like they are a little bit harder and/or less stretchy than an ordinary rubber gasket. They may also be a little more difficult to install on the joint, and may require a little higher force to home the pipe in the field. Also, there will be an orange stripe on nitrile gaskets and a yellow one on neoprene gaskets.

Why does it take up to 5 to 8 weeks to receive orders for nitrile/neoprene gaskets or connectors?


The base compounds used to make nitrile and neoprene are expensive and have a very short shelf life. As such, HK generally orders the compound only when it’s needed to avoid costly spoilage. In addition to the shipping time, some time is also required for the compound to acclimate to the environment before it can be processed into a finished product. Also, splicing nitrile gaskets is challenging and our production team needs more time to devote to this part of the process. Finally, our QC personnel need time to thoroughly check the gaskets to ensure that the product we deliver will meet all required specs. No gasket is shipped unless we are 100% certain it will perform well in the field.

What is the life expectancy of rubber gaskets once installed in the field?


Provided the correct material is used for the conditions, gaskets will continue to perform properly for the life of the structure or pipe in which they were installed.

What are the primary uses for nitrile and neoprene gaskets and connectors? Can you explain what elements, soil conditions and chemicals require these materials?


These rubber materials are primarily going to be used in gaskets or connectors when they are likely to be exposed to petroleum-based substances, such as oil, jet fuel, vehicle fuel or grease. Exposure to these substances likely would cause gaskets and connectors made of ordinary rubber compounds to deteriorate more rapidly than they are designed. Nitrile and neoprene gaskets and connectors will maintain their physical properties and provide the intended seal even when in contact with petroleum-based materials. Please note that gaskets and connectors made from these compounds can take as much as 5-to-8 weeks to deliver and cost significantly more than ordinary rubber components.

Specifications and Certification

Which ASTM and CSA standards govern rubber gaskets?


ASTM C1619 contains the gasket performance standards referenced by ASTM C361, C443, C1628, and C1677. Most of the gaskets supplied by Hamilton Kent meet or exceed the requirements of C1619 Class C and Class D for oil-resistant gaskets. But we also supply gaskets to meet Class A and Class B requirements. Our gaskets also meet or exceed the requirements of CSA 257.3.

How do I know the gaskets I receive from HK meet the required specification?


Applicable specifications are printed on each gasket. Additionally, Hamilton Kent can provide documentation showing the quality assurance testing completed on these gaskets according to the specifications for your project. HK does not and will not cut corners. Rest assured that the gaskets you receive are the correct ones for the project. HK is ISO 9001-2015 certified and we have proven quality control system in place.


How long can I store my regular rubber gaskets before they can no longer be used?


Assuming they are kept in a dry location, free of ozone and away from UV light, regular rubber gaskets can be stored up to three years after their manufacturing date and safely remain within specifications. Beyond three years after manufacturing, HK recommends that the durometer (hardness) of the rubber be tested to ensure it is still within specifications before installation. Contact the HK technical department for recommendations on durometer (Shore A) gauges. A sample gasket can also be returned to an HK plant for testing. After four years of storage, Hamilton Kent recommends testing of the gasket material before usage, which can be done in our quality control lab.

How long can I store my nitrile/neoprene gaskets before they can no longer be used?


If they are stored in a dry location, free of ozone and away from UV light, nitrile gaskets should remain within specifications for at least two years after their manufacture date. Beyond two years, the durometer (hardness) of the rubber should be checked prior to each shipment of these gaskets to ensure they are still within specifications. You can contact the HK technical department for recommendations on durometer (Shore A) gauges. A sample gasket can also be returned to an HK plant for testing. After three years of storage, Hamilton Kent recommends testing of the gasket material before usage, which can be done in our quality control lab.


What affects the price of gaskets?


Base compounds used to make rubber gaskets such as polymers and monomers are the same chemicals used to make any rubber product. Manufacturers of car tires are the biggest consumers of these base compounds. Like most products, as the demand for these compounds increases, shortages can occur and drive up the prices. Additionally, the cost of petroleum products can factor into the cost of our gaskets and connectors, not only because of the raw materials, but also for transportation. We work very closely with our suppliers to try to mitigate these effects for our customers.

Why are SuperSeal™ pre-lubed gaskets more expensive than standard profile ones? Is it the process to make them?


There are several reasons why the Tylox® SuperSeal™ gaskets are more expensive than traditional profile gaskets. First, due to the delicate nature of the rolling tube and the challenge to manufacture it perfectly, there tends to be a higher scrap rate for this gasket type. Second, the rolling tube requires additional rubber material in the production process. Third, each SuperSeal™ gasket requires injection of a silicone lubricant into the tube and subsequent mechanical rolling of the gasket to spread the lubricant within the tube, which adds to the labor and machinery time and cost. As lubricant is not required for assembling of the joints, the final cost to the owner of a gasketed joint should be similar to use of profile or O-ring gaskets.


How much deflection do your connectors allow?


All of our connectors have been designed to meet and tested according to ASTM C923, which requires testing at 7° of axial deflection. Hamilton Kent does not recommend use of our connectors for deflection greater than 7°, however testing for such applications can be done by the concrete structure supplier.

In what situations is it better to use cast-in connectors or mechanical connectors?


Hamilton Kent recommends any connection between a concrete structure and a pipe with an outside diameter (OD) of greater than 18” be made with a cast-in connector. With the curve in the wall of a typical manhole, getting a good seal between a boot connector and the cored hole in the manhole is very challenging. Cast-in connectors are designed to follow the curve of the formed hole and provide an excellent seal with the inserted pipe. Additionally, the portion of the rubber connector embedded in the concrete ensures a much greater seal than a mechanically-installed boot connector.