Lead weights are ubiquitous objects. There are, however many good reasons why lead metal is used where large weights are required.
Lead has a high density; it is soft and easy to work, has a low melting point so it is easy to cast either as pure lead or as a lead alloy and is relatively inexpensive often produced as a byproduct of silver mining.
Lead weights find many uses particularly in ships and sailing vessels and in the construction industry, where large leads weights of several tens of thousands of pounds or even hundreds of thousands of pounds are often required.
This article describes Nuclead’s experience and experience in lead weights and their uses.
Nuclead’s Capabilities
Many sailing ships use cast keel lead weights for counterweights. Nuclead can produce lead castings in all sizes and weights up to 100,000 lbs. Castings can be made either in 99.99% pure lead or any percentage of lead alloy, including antimony, tin, zinc, bismuth and copperNuclead also has the capabilities to produce counter weights in any size including orders for 300,000 pound lead crane weights, counter balance weights for elevators, movable bridges and fork lift trucks, custom counter weights for defense applications and ship ballast, which includes counterweights for all sea going vessels including navy ships, commercial vessels and sailing ships.
Here are some of the standard forms for lead weights that Nuclead can offer:
- Pure lead ingots, up to 60 lbs. (approx. size 3″ x 4″ x 20″ loaf shape)
- Lead slugs, with or without holes
- Lead block – and size, weight or material
- Lead round – and size, weight or material
- Lead balls
Nuclead can machine and fabricate any lead weight to your custom specifications; this includes adding Holes, slots or other features which can be machined into the lead weights, or various surface finishes per custom drawings.
Lead Weights used for Ballast in Ships and Sailing Vessels
Lead because of its high density, relatively low cost and resistance against corrosion, is used for ballast in ships and sailing vessels. Lead ballast is used to counter buoyancy to provide stability and in sailing ships to create a counter force to the wind on the sails
Lead ballast is either external ballast, which is built into the keel or is internal ballast which can be in many forms including lead blocks, lead balls or lead ingots.
Lead Ship Ballast is used to provide distribution of weight, to counteract buoyancy and to provide stability. Lead ballast is used in sailboats to provide moment to resist the lateral forces on the sail. The lead weight is typically kept as low in the water as possible to provide the maximum righting moment that can be extracted from the given mass.
Ballast Lead comes in a variety of sizes, shapes and grades; common is Machine Lead which is around 1-4% Antimony content the remainder is Pure Lead
External Ship Ballast
On many modern vessels, the keel is made of high density lead casting, including machined or cast-in fixtures. In some cases the lead keel can be cast in one piece, called a solid pattern or if it must be cast in pieces it is referred to as a split pattern. Lead keel castings can range from 100 lbs. to 200,000 lbs., and can take virtually any shape or size.
Lead weight in the keel, significantly lowers the center of gravity and thus prevents to boat from tipping over. The lead weight also helps the boat to move forward rather that slipping to the side thus converting the sideways motion of the wind into forward motion. When moving forward the keel also generates lift to counter the tipping moment caused by the wind on the sails.
Lead keel bulbs are often used in sailing vessels, these provide additional turning moment to prevent tipping and allow the vessel to sail closer to the wind.Sheet Lead can also be used for ballast applications when additional weight is required for wrapping Lead Keel Bulbs and Fins.
Internal Ship Ballast
Historical forms of ballast carried inside the hull were stones or sand. However lead ballast provides a more flexible and easier to use alternative. Internal lead ballast can consist of many forms including lead shot, lead ingots and lead blocks ranging in size from 10 lbs. and up.
Lead shot is an option for ballast requirements when space is tight. Lead shot is also excellent for trim ballast applications, keel centerboard ballast fills and lifting keel applications.
One piece internal lead keel castings are also sometimes used.
Lead Weights in Construction
Often lead weights find uses in construction in the form of lead counterweights. This can either be in the construction equipment or in the building or structure itself. Lead Counterweights in construction equipment
Construction cranes require large lead weights, to provide a counter balance to the load being moved. A crane is basically a mechanism that balances the load to be moved with a lead counterweight. Since the counterweight is usually close to the tipping point, it will be significantly larger than the load weight. Some cranes increase their load capacity by using hydraulic mechanisms to move the counterweight away from the tipping point.
Lead weights are also used in pile drivers. A pile driver is a mechanical device used to drive piles, typically made of timber, steel, or reinforced concrete, into soil to provide foundation support for buildings or other structures. A typical pile driver includes a heavy lead weight placed between guides so that it is able to freely slide up. The lead weight is raised and then released so that it impacts the pile drives it into the ground.
Other smaller pieces of construction equipment such as fork lift trucks, lifts or earth moving equipment may use lead weights for counterweights or to increase traction.
Lead Counterweights in buildings and other structures
Lead weights are often permanently installed in many structures. In most cases these are counterweights such as in the case of elevators where the lead weight is used to balance the weight of the riders and to reduce the load on the motors.
Lead counter weights are also used in movable bridges, in a similar manner to elevators to counter the load of the deck. A drawbridge style of moveable bridge uses a lead counterweight to continuously balance the span, throughout the entire upward swing in providing clearance for boat traffic. In a vertical-lift bridge part of the span is raised vertically, staying parallel to the ground. This kind of bridge uses smaller counterweights than a draw bridge since it only needs to balance weight of the deck. This allows for stronger material to be used and makes this kind of bridge suitable for heavy traffic such as railroads.
Lead counter weights are also used in certain amusement rides.
Conclusion
Lead weights for counter balance uses range in size from a few pounds to hundreds of thousands of pounds. Counter balance lead weights take many forms from lead balls to lead ingots to lead castings.
No matter what the size or the form Nuclead has the expertise and experience to deliver lead weight, lead ballast and counterweight products to specification.