Quality Products For Professionals Since 1916 ISO9001:2015

Frequently Asked Questions


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Information we need

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TAMPI -> Temperature, Application, Medium (flow), Pressure, Inside Diameter

Plug Specifications

Petersen PeteStop™ and Multi-Flex® Plugs and Inflatables are made from synthetic materials generally with a shelf life many more years longer than molded rubber plugs. We do not test the final product for length of life but have anecdotal feedback they have been used for years before returning for repair, testing, and recertification. Every project is different so only length of life generalizations are possible. Please contact Petersen Engineering for details.

The MultiFlex® and PeteStop® standard plugs are made with synthetic materials and have an indefinite life expectance so they will probably be fine for many years. However, it is suggested that they be tested annually for leaks because we do not have a record of long-term durability for any of our manufactured items. The Molded rubber plugs have a shorter life because the rubber deteriorates over time and should be tested annually but generally should be replaced after three years. All plugs should be stored out of direct sunlight and in dry ambient temperature conditions.

The plug inflation pressure generally stabilizes in several minutes for small plugs and a couple hours for very large ones. We recommend continuous monitoring of plug pressure, pipeline pressure, temperature, flow and pipeline conditions while the plug is in service.

Plug Installation

It can be installed horizontally or vertically and into a horizontal or vertical run of pipe It can be installed into unique circumstances such as ROV, tunnel, or rock

  • It can be inflated from the end or from the side
  • It can be lowered into place with a crane or hoist It can be rolled in on wheels or other device It can be inserted through a hot tap
  • It can be inserted through a hole smaller than the pipe size It can be installed via ROV
  • Other placement options are available

Water is not compressible so is less dangerous than inflation with air or another gas. Water is especially preferred for large plugs and high pressure but it is still a judgement based on what is in the pipeline and the consequence of a plug failure for any reason.

  • Yes. We have many options available from hot tap insertions to multi-segmented mechanicals.
  • We test plugs only for rated size pipeline but understand they are sometimes used in a smaller diameter pipe. As the size is reduced there will be more wrinkles in the outer ply so general more seepage past the plug. This may or may not provide an acceptable block.

Yes. We have many application specific options available. Our very flexible Multi-Flex TM plugs excel in this application.

  • The hydrocarbon resistant Multi-Flex® plugs have a 200°F maximum service temperature and may be modified for up to 400°F.
  • Multi-Flex® Plugs may be customized for most chemical resistance requirements. Multi-Flex® plugs have a much higher puncture and tear resistance than rubber molded Plugs and may be customized with Kevlar for even greater puncture resistance.
  • None of our inflatable plugs can withstand 600F and weld splatter can damage them.
  • The temperature of the pipe can sometimes be reduced by flooding the plug area with water.
  • The splatter can be reduced somewhat by the welding technique, we can add a Kevlar outer ply, or the plug moved further from the weld area.

Based on our best information the Kevlar Viton B material used in manufacturing the 114-0245-KV plug provides resistance to Hydrofluoric acid. It is still recommended that any product be tested under actual environment as conditions may vary considerably and we do not have the facility to perform chemical tests.

NOTE: DO NOT pull on the Inflation hose to remove the Inflatable Plug

  • Disconnect the air source and open any valve on the Inflatable Plug.
  • Petersen recommends using a Vacuum Generator to deflate larger Inflatable Plugs.
  • Water Deflation - Disconnect the water source from the Inflatable Plug.
    • Connect the hose to the water outlet.
    • Verify that the water outlet hose drains into a tank or area that can collect the drained water.
  • Monitor and track the output as needed. Removing the Plug
  • Carefully remove the Inflatable Plug only after it is completely deflated.

Customers typically request EPDM or Viton elastomers for a flare line. EPDM is generally desired for H2S and Viton for temperatures above 325°F.

Inflatable plugs generally remain inflated when disconnected temporarily from an inflation source. However, an inflatable device does not have perfect impermeability and will lose pressure in time, even vehicle tires. The pressure also will change with changes in temperature and head pressure. Petersen recommends monitoring and maintaining inflation pressure of inflatable plugs.

Plug Applicaton

Safety is our top priority. All pipe plugs must be blocked or anchored adequately against a force equal to the head pressure times the cross-sectional area of the pipe. Debris or protrusions in the pipeline can damage a seal or rupture inflatable plugs. NEVER use an inflatable plug when its failure could cause injury or catastrophic damage or as the only means of protection for personnel working downstream. NEVER use a test pressure greater than the capacity of the weakest pipe or component in the system. Actual conditions vary so user must accept full risk and responsibility for the selection and use of any product.

The maximum pipeline head pressure is generally 50% of the plug maximum inflation pressure. It can vary based on actual pipeline conditions and the product being blocked.

The head pressure is considered the maximum differential pressure up and down stream of the plug. If the pressure is 100 psi up stream and 50 psi downstream of the plug, the head pressure is 50 psi. With a 120”WC vacuum (4.33 psi) on one side of the plug and no vacuum or pressure on the opposite side of the plug, the head pressure is 4.33 psi.

The plug is used where there is a small opening for inserting a plug and/or when greater pressure, chemical, and temperature characteristics are desired.

Our Multi-Flex plugs such as the 113 to 127 series plugs have the highest minimum to maximum size ratio in the industry but the fabric reinforced outer ply develops wrinkles as the pipe diameter reduces thus allowing more seepage past the plug. They can be customized for testing a specific size but a mechanical or rubber plug if more typical for testing.

  • The Mechanical and Molder Rubber plugs create the best seal for pipeline testing.
  • The standard Multi-Flex plugs may allow some seepage but generally create an acceptable seal, though typically not for pipeline testing.
  • The MultiFlex plugs may be customized at extra cost with an enhanced seal for testing that includes sealing any longitudinal and circumferential sew seams.
  • Pipeline conditions such as contamination and corrosion may also influence the seal.
  • A leak tight sealed best achieved with a double block and bleed plug or multiple plugs with a bleed tap between them.

Our 128 and 129 PeteStop TM Inflatable Line Stops are designed to be inserted through a hot tap and can provide for most requirements.

A pipe plug should generally about ½ the pipe diameter away from any obstruction or welding to allow for plug stretching, imprecise location, and weld splatter. The pipe plug should be located in an area the pipe does not exceed the plug temperature rating. The pipeline temperature This is a rule of thumb suggestion may not be appropriate for every project.

General Information

No. We do not.

No, we can train you or your contractor to use our equipment. Contractors on this link are also available to install our equipment - click here to view.

Typically, we categorize them by Inflatable or Mechanical. We have plugs for most size, pressure, and temperature requirements.

Many items are in stock for same day shipment. Standard items out of stock generally in 2 - 3 days. Items built for a specific project are manufactured often can be shipped in 2 - 3 weeks. Expediting is usually available upon request

Per the vendor, yes, it is certified

We are just north of Milwaukee at 421 Wheeler St. Fredonia, WI 53021

All Petersen manufactured items are produced in the USA. Some items sourced from others may be manufactured in a country listed in the specifications.

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