Plugging tubes is one of the most conventional ways to repair shell-and-tube heat exchangers.
This is necessary when the tube is found to have some form of wear and tear, such as holes and cracks, which impacts the performance of the system. After undergoing testing, leaking tubes can be plugged to rectify the issue. The repair is done by installing a mechanical or welded plug in the tube sheet area, and the plugged tube should be pierced to prevent any potential blowout while maintaining the tube plug's integrity. This article goes through three methods you can use to plug tubes in heat exchangers.
Mechanical Plug
The mechanical plug method is creates a metal to metal mechanical contact seal without requiring any welding. It is more appropriate for situations where friction-fit tapered plugs aren't suitable due to various pressures, temperatures, environments, and specific conditions. The mechanical plug is ideal for plugging tubes exposed to an effective pressure up to 7,000 psi and can withstand up to 2,000°F. This is more suitable for tubes exposed to higher temperatures and higher pressure. Before using this method, you will have to consider these conditions:
- Whether the plug and tube have different properties and metallurgy
- Interior surface of the tube – is it severely damaged and corroded?
- State of the mechanical joint connecting the tube to the tube sheet (in rolled tubes)
- Location of installation – is it exposed to highly corrosive conditions?
You should track the location and quantity of plugged tubes using a map to observe a propensity for tube failure at certain periods before fully replacing the tube. Additionally, you can consider checking the pressure loss regularly as some heat exchangers will not function properly when dipping below a certain level.
Tapered Plug
The tapered plug method is suitable for lower temperatures and lower pressure services than the mechanical plug method. When it comes to using tapered plugs, tubes should be pierced before using to prevent a plug blowout, posing a safety hazard. However, if this is not applicable, the tube should be pulled or other methods such as draining liquids from the tube and attaching the plug to the tube sheet instead to prevent any danger. These are the following conditions it should meet before using this method:
- 200 psi or less operating pressure in the shell-side
- 400°F or lower operating pressure in the shell-side
- Mechanical joints in tube-to-tube sheet should not be welded but expanded (do inspect for tube thinning to prevent seal failure)
Condenser Plug
The condenser plug is an ideal solution for tube plugging lower pressure heat exchangers and can be easily installed using the Hex Capture Drive. The plug available on our online store can be installed into the tube using a standard 3/8" square drive torque wrench and will be suitable for a tube with an inside diameter (ID) of between 0.580" and 1.200". It also has a variable installation depth, where the plug can be inserted at a suitable point to prevent contact with the tube sheet's corroded areas. The following considerations should be met when using this method:
- Heat exchanger with an operating pressure of less than 250 psi
- Heat exchanger with operating temperature of below 300°F
- The extent of corrosion resistance and chemical resistance required
Visit Torq N' Seal® for Your Tube Plugging Needs
With over three decades of heat exchanger tube plugging and maintenance, Torq N' Seal® is highly experienced and knowledgeable in this aspect of the power industry. Therefore, if you require any tube plugs for your repair needs, you can visit our online shop, where you will find top-quality tube plugs that are highly effective and durable. We are committed to bringing our local and international customers the very best in our products and services.
For more information about our tube plugs, please do not hesitate to get a quote or contact us today!
