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Step 2: As the lead levels rise, heat is discontinued from the bottom up to allow the lead to cool and solidify. Lead shrinks as it cools and will form a gap between the wall and the fabrication. By slowly cooling the lead from the bottom up, more lead can be poured into areas that are shrinking or not level as well as allow for air bubbles that could turn into voids to rise to the top. A highly controlled process can reduce the shrinking of the lead to around 1/32” to 1/16”. This is why it is important that the lead pourers have a clear view of all areas of the fabrication, as hidden areas are at a greater risk of lead shrinking away from the walls. This process is continued until the fabrication is filled to the desired filled to the top or desired fill level. The fabrication is then ready to be sealed and welded shut.
Considerations when designing fabrications for lead pouring
• Fabrications should be made of steel or stainless steel and must be strong enough to support the weight of the lead and at least ¼” thick to reduce the risk of temperature deformation.
• For health and safety reasons, MarShield does not accept fabrications that have been tinned or painted. The inside of the fabrications should be debris and moisture-free.
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• Lead Shrinks as it cools. For radiation shielding, account for this in the design and allow for 1/16th to 1/8th inch of shrinking from all edges.
• There is the potential for deformation and the steel plates moving. This should be considered when deciding on tolerances and pieces that will need to fit together. MarShield can work with you to design bracing that will help with movements during the pouring process.
• Welds should solid on the fabrication before welding to ensure no lead will leak during the pouring process.
• Placement of lifting points should be considered and installed before the pouring of lead to ensure that the fabrication can be moved vertically.
While this type of lead pour procedure is used mostly in the Nuclear Industry, many of the above tips and procedures can also be applied to building test weights or any other lead-filled products to ensure the highest quality. MarShield is a leading expert in nuclear fills and works with numerous clients in the nuclear industry. If you would like to find out more information about MarShield’s Lead Pours, you can visit the MarShield website or you can contact MarShield directly, and we will help you find the best radiation shielding solution for you.
MarShield Custom Radiation Shielding Products provides radiation shielding solutions for the Medical and Nuclear Industries and is a division of Mars Metal Company. Contact us today to discuss your unique radiation shielding needs!
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