This Week’s Subject: Anode Installation Location

Question: Joe, what is the proper installation location for an anode to protect steel pipe from corrosion?

Answer: First, it’s important to follow your company’s construction standards and/or O&M procedures because they vary. But generally an anode can be installed vertically or horizontally. The typical, preferred method is to install the anode vertically, but soil conditions or underground access beneath the pipe may prevent this. In that case, you can install it horizontally.

For an anode to function properly, a minimum distance must be maintained between the pipe and the anode. This distance may vary, but it’s usually a minimum of 1 foot away (offset) from the pipe or below the pipe.

Tip: Do not remove the anode from the cloth bag, which contains gypsum and bentonite. These materials help to absorb and retain moisture from the soil. This improves the efficiency of the anode by reducing electrical resistance. During installation, the anode is activated by wetting the cloth bag with water.


This Week’s Subject: Cold Flow Stabilization

Question: Hi Joe – When I’m using squeeze-off tools to stop gas flow in plastic gas mains, my supervisor tells me to allow for cold flow stabilization. Why do this?

Answer: Your supervisor is right on! Cold flow stabilization is simply the relaxation of the polyethylene (PE) pipe, due to the stress of the squeeze-off procedure. For an effective squeeze-off, it’s important to ensure relaxation allowance once the mechanical or hydraulic squeeze tool fully compresses the pipe. This is accomplished by allowing 1 minute per inch of the pipe diameter being squeezed. Butthe time should be doubled for temperatures below 32°F.

Examples: 4 minutes are allowed for 4-inch-diameter pipe at 80°F, and 8 minutes are allowed for 4-inch-diameter pipe at 20°F.

Tip: Hydraulic squeeze tools involve a specific gauge pressure that’s attained before allowing for cold flow stabilization. This gauge pressure will drop during cold flow approximately 150 to 200 psi, requiring re-pumping to the original pressure for a completed squeeze-off.

This Week’s Subject: Welding on Transition Fittings: Polyethylene (PE) Protection

Most company procedures prohibit the practice of shortening/cutting of a steel transition fitting because, during welding, the polyethylene (PE) material and/or the connection to the steel could be damaged.

Why is this practice prohibited? When the pipes are buried in the ground, there is a potential pull-out from the effect of thermal expansion and contraction. The result can be dangerous gas leaks, underscoring the importance of protecting the PE side of a transition fitting from heat.

Tip: Certanium Heat Shield, a nontoxic, putty-type material that withstands temperatures to 3000°F, can be used effectively to prevent heat transfer that can damage transition fitting components (metal rings, O-ring gaskets) and PE pipe. Heat shield is also effective in various welding-related applications that are performed near heat-sensitive materials and equipment.

This Week’s Subject: Polyethylene Heat Fusion Equipment

Have you ever struggled with trying to remove dirt residue from the jaw serrations?
Often times a wire brush doesn’t cut it because the residue gets caked up and is very hard to remove.

Hint: Try using a thin screwdriver to carefully loosen the packed residue by running it down the jaw serration grooves and then wire brush all upper and lower jaw serrations thoroughly. This will save on equipment cost maintenance, and ensure that PE pipe/fittings do not slip while performing butt fusion.The last thing you want to do is excessively clamp down, resulting in equipment damage (when pipe slippage is really caused by the lack of grip due to residue build-up). This will wear down the clamp knob and/or the jaw assembly, and replacement parts are very costly.