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Frequently Asked Questions

What is the MG Coupling?

The MG Coupling is a heavy-duty, cast iron, no-hub coupling that is used primarily for commercial, industrial, and municipality applications. Although we are mostly used for underground installations, the MG Coupling is also used above ground as well.

What are the material specifications of the MG Coupling?

The MG Coupling is made out of:

  • Cast iron clamps (ASTM A-48//A-48M)
  • Neoprene gasket (ASTM C-564)
  • Stainless Steel 18-8 nuts and bolts (ANSI B18.2.1 & B18.2.2)
  • Coupling manufactured to meet ASTM A-1056 standards, the only coupling on the market to do so!

Can the MG Coupling be installed on plastic, or carbon steel pipe?

No, the MG Coupling is only used for cast iron soil pipe. This includes sanitary soil systems, storm water drainage pipes, and vent piping. The MG Coupling can be installed in any application that uses cast iron pipe.

How do you install the MG Coupling?

Installing the MG Coupling is a simple 4 step process:

  • You place the neoprene gasket on one end of the pipe and the clamp assembly on the end of the other pipe.
  • Fit both hubless pipe ends into the gasket, firmly butting them against the internal center rib between them.
  • Pull the loose clamp over the gasket, keeping the bolting flanges evenly separated.
  • Accurately torque nuts to 175 in-lbs.

How much does the MG Coupling cost?

At MG Coupling, we work diligently to make sure that you are receiving the best price possible. Because the coupling is a standard item, we competitively price the coupling against other heavy-duty couplings on the market today, including stainless steel bands. We work to guarantee you the lowest price!

How easy is it to install an MG Coupling?

Very easy! From 1.5" to 4" our couplings only have two stainless steel bolts to tighten to 175 in-lbs of torque. While our 5"-10" couplings have a total of 4 bolts to tighten. You will find our couplings to be the easiest and fastest to install than any other no-hub coupling on the market. We will give you free MG torque wrenches that are pre-set to torque to 175 in-lbs. This saves you time and money on the job!

How does soil type affect the corrosion of couplings?

The major soil conditions which affect corrosion and must be considered are type, drainage, resistivity, acidity, and particle size. Also, the ditch back environment is a man-made disturbance of the natural environment, and can adversely affect these soil conditions.

  • Type: Soil may consist of sand, loam, clay, mulch, or any combination of all of these. The most corrosive is mulch, the least is sand.
  • Drainage:Soil with poor drainage are the most corrosive while well-drained soils are the least damaging to couplings. *Except for cinder fills.
  • Resistivity:While oxygen concentration and acidity can affect this, normally low resistivity soils are corrosive while high resistivity soils are not.
  • Acidity:Neutral soil is least corrosive (7 pH). A soil with a pH>7.0 contains salt, therefore accelerating corrosion (think desert soils), while a soil with a pH less than 7.0 is highly acidic and corrosive.
  • Particle Size:Large soil particles can allow oxygen to penetrate to the buried metal product, thus accelerating corrosion. If an area with an abundance of oxygen is next to an area of a limited supply of oxygen, a differential aeration corrosion cell is created, which is the most common type of corrosion.

Why is stainless steel susceptible to corrosion?

Stainless steel is susceptible to crevice corrosion, or "concentration cell" corrosion, depending upon the shape into which it is fabricated and the degree of crevices or inside corners formed during its fabrication. Even though S.S. is resistant to corrosion due to an oxide coating, this coating can be damaged during the fabrication process. If so, the exposed area is vulnerable to corrosive attack that can affect the whole coupling.

So, how does the MG Coupling resist corrosion better than stainless steel?

The actual design of the MG Coupling resists the effects of soil corrosion because of the unique combination of cast iron clamps and stainless steel bolts. This combination of metals creates what is called a Galvanic Cell. This cell reverses the current flow between the two metals and provides full cathodic protection to the bolts and nuts, which hold the joint together.

Can you elaborate on the "Galvanic Cell"?

When two dissimilar metals are in electrical contact with each other and are exposed to a common electrolyte (soil), a cell is formed in which galvanic (differential aeration) corrosion occurs at the anode metal (-), while the cathode metal (+) is protected. The MG Coupling forms such a cell, and tests show that the stainless steel bolts and nuts are receiving a full level of cathodic protection from the cast iron clamps (the coupling body). Since the S.S. nuts and bolts are lower in the galvanic series (below) than cast iron, they are cathodic to the coupling body, which become anodic and protect the bolts and nuts from corrosion. Now, because the coupling body and nuts and bolts are relatively close in the galvanic series, and the coupling body is much larger than the bolts and nuts, the current between the two metals is small, causing no damage to the coupling body, which is anodic.

Is the MG Coupling tested periodically?

Yes, the MG Coupling is independently tested every few years to make sure our couplings meet our standards of exceptional quality and durability. As such we conduct the following tests: Hydrostatic, Deflection, Shear, Thrust, Vacuum Infiltration, Infiltration, and Impact tests. The MG Coupling also has the highest deflection rating on the market today.

Where can I find more specific information about the MG Coupling?

You can visit our downloads page here, where you can view many different documents regarding the MG Couplings specifications, certifications, and more detailed installation instructions.

One More Question?

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