Testing a weighbridge, checking a crane scale or calibrating a floor scale: all of these require heavy weights. The measuring itself is the easy part. The real work lies in moving hundreds of kilograms or even tonnes of steel and cast iron, without accidents and without damaging the weights.
In this article we bring together the points we encounter in practice, from lifting a 20 kg block weight to transporting mass pieces of 2,000 kg. How the calibration of such weights is carried out is explained at calibrating heavy weights.
Which designs are there?
Heavy test weights come in various forms, each with its own way of handling:
- Block weights of 20 kg and 50 kg, usually of cast iron, with a handle for picking them up by hand or with a hook.
- Stackable block weights with a shape that keeps them stable on top of each other, handy for floor and pallet scales.
- Mass pieces from 100 kg to 2,000 kg, rectangular or cylindrical, with lifting eyes or openings for the forks of a forklift.
- Weight baskets and weight trolleys, in which a number of smaller weights are used together as a single load.
Which design suits depends on what you are testing and which equipment is available on site. At a weighbridge a forklift or crane is often available; at a floor scale in a production hall, not always.
Manual lifting: up to what point is it responsible?
Block weights of 20 kg are often moved by hand. That seems light, but during a test dozens are soon picked up one after the other, sometimes from the floor and with a twisted back. In occupational health practice the NIOSH method is used, which applies 23 kg as the upper limit under ideal conditions. Under less favourable conditions, such as lifting from floor level or frequent repetition, the responsible limit is lower.
Some practical measures:
- use a sack truck, a roll container or a table at working height instead of lifting from the floor every time;
- do not have 50 kg weights moved by hand by one person, but use a lifting aid;
- wear safety shoes and gloves with grip, and keep the walking route clear;
- set weights down; do not drop them or slide them over the edge of a scale.
Lifting and hoisting
Lifting eyes
Mass pieces have fixed lifting eyes or screw-in eyebolts. Before lifting, check that an eyebolt is fully screwed in and sits flat against the weight. An eyebolt that is loaded at an angle can take far less than its nominal capacity. With two lifting points, use a suitable lifting chain or lifting beam so that the eyes are loaded as straight as possible. Only use lifting gear that is periodically inspected and suitable for the mass, and never walk under a suspended load.
Forklift
Weights with fork openings or on a pallet are moved with a forklift. Mind the lifting capacity: the value on the type plate applies at a certain load centre. If a mass piece sits far forward on the forks, the forklift can lift less. Drive with the load low and set the weight down gently, especially on the deck of a weighbridge or the platform of a scale.
Weight baskets
A weight basket full of block weights is heavier than it looks. Check the maximum load of the basket and make sure the weights cannot shift. If the basket is part of the test load, the mass of the basket must also be known, preferably with a certificate. Otherwise an unknown part of the load is included. More about testing with large loads can be found in Weighbridge checks and maintenance and Using a crane scale safely and accurately.
Planning transport
With heavy weights, safe working starts with good planning. Go through these points beforehand:
| Point | What to look at |
|---|---|
| Total mass | Number and nominal value of the weights, plus baskets and pallets |
| Vehicle | Payload, axle load and capacity of the tail lift |
| Securing the load | Straps, anti-slip mats and blocking, so that weights cannot slide or tip |
| Loading and unloading | Which lifting or hoisting equipment is available at departure and on site |
| Route on site | Doors, thresholds, slopes and the load-bearing capacity of floors and lifts |
| Weather | Keep weights dry, cover them in rain, no ice or snow on the weights |
Take the certificates with you or make sure they are available digitally. An inspector or auditor will want to see which weights were used and whether their calibration is current.
Storage: dry and not on the bare ground
Heavy weights often stand for years in a corner of a warehouse or outside next to a weighbridge. That is exactly where most problems arise. Preferably store them indoors, in a dry room. Place them on a pallet, a plastic sheet or beams, not directly on concrete, sand or gravel. A bare floor retains moisture, and moisture under a weight means rust.
Only stack weights that are designed for it. Keep lifting eyes and fork openings clear and clean, and with heavy mass pieces check that the floor can bear the point load. A fixed, marked place with the identification of each weight prevents mix-ups. More general tips are given in Storing and handling calibration weights.
Paint, rust and dirt
On cast iron and steel weights, the paint layer protects against corrosion. Damage from a fork, chain or knock is an opening for rust. Rust first makes a weight heavier, because the iron binds oxygen and water. As soon as the rust flakes off, the weight becomes lighter. In both cases the mass changes.
Dirt also counts. We regularly see mass pieces with caked mud in the fork openings or oil and dust on the top surface. For a 1,000 kg weight in class M1 the permissible error is 50 g, and a handful of mud soon weighs more than that. Clean and dry weights after use. Do not touch up the paint yourself, because paint has mass too: have the weight treated and then recalibrated. The choice of material partly determines how sensitive a weight is, see Cast iron or stainless steel weights.
Buy or hire?
Owning heavy weights is convenient if you use them often. They do, however, require storage space, lifting and transport equipment, maintenance and periodic calibration. Hiring can be more favourable if you only need the weights a few times a year, for example for an annual weighbridge test or a proof load test.
- Buying is the obvious choice with regular use, your own lifting and hoisting equipment and sufficient dry storage.
- Hiring suits occasional use, projects at changing locations or when you do not want to arrange storage and maintenance.
Heavy weights can be bought via mass pieces and block weights in our webshop. For temporary use you can hire weights.
How MASSLAB helps
MASSLAB has its own transport and equipment for weights up to 2,000 kg. We collect your heavy weights, clean, derust, paint and adjust them where necessary in-house, calibrate them and bring them back. If you only need the weights occasionally, you can also hire them from us. More about our approach can be found at calibrating heavy weights.