OSHA requires that blocking used as part of an energy control procedure be capable of withstanding the load. For cribbing, the bearing area times the compressive strength of the wood gives the maximum load per stack. The load per stack depends on how many stacks are used and the geometry of the load. Never guess — an overloaded cribbing stack can fail explosively

A wooden block that looks intact may be rotted internally or have compression damage from prior overloading that is invisible externally. Blocks that have been used under a hydraulic jack while wet may appear fine but have internal degradation. Oil-saturated wood has significantly reduced compressive strength. Inspect every piece before building a crib — failed blocks must be removed from service immediately

Softwood (pine) cribbing is inadequate for heavy vehicle or machinery loads — hardwood (oak, elm) or engineered plastic cribbing with a known rated capacity must be used. Manufacturer-specified safety blocks (die blocks, press blocks) must be used on power presses — improvised blocking violates OSHA 1910.217. Steel blocks must be used where wood is prohibited by the equipment manufacturer

Improvised blocking from construction scrap, shipping pallets, or random lumber is one of the leading causes of blocking failures. Pallet wood is notched and weakened. Construction scrap may be any species, moisture content, or grade. Dedicated blocking and cribbing should be cut to standard sizes, inspected regularly, and stored clean and dry. Paint the ends of blocks for easy identification

Cribbing placed on soft ground, asphalt in hot weather, gravel, or uneven surfaces can shift and sink under load, destroying the stability of the cribbing stack. On soft ground, use wide timber mats or steel plates under the cribbing base to spread the load. On concrete, ensure no cracks or voids beneath the point of contact. Never crib on slopes without wedged levelling

Vehicle manufacturers specify designated lift and support points — frame rails, axle housings, suspension cross-members. Blocking placed under body panels, rocker sills, or non-structural areas causes body damage and catastrophic blocking failure as the panel collapses. For construction equipment and machinery, the equipment manufacturer’s service manual specifies blocking points. Using any other location is not permitted

The 3:1 height-to-base ratio is the industry standard for cribbing stability. Each layer must be rotated 90 degrees so the blocks interlock — like log-cabin construction. Layers that are not rotated slip off each other under lateral load. The top layer must bear fully on the load contact point — partial contact at the top concentrates stress and causes splitting

A cribbing stack that rocks or has a gap at the top contact point will tip under load. Wood wedges (never metal wedges, which can slip) are used to fill gaps and eliminate movement. Once wedges are in place, tap them firmly and check that the stack is solid. Any movement in the cribbing after the load is lowered onto it requires re-setting before the working zone below is entered

Before any person enters the area under a raised load, a second trained person must physically check the blocking setup: correct points, stable surface, no rocking, stack ratio acceptable, full contact at top, and wedges secure. The person who places the blocking is not the person who authorises entry — two-person verification catches errors that are invisible to the person who placed the blocking

OSHA 1910.147(c)(4): written energy control procedures must identify the type and magnitude of hazardous energy and the methods for controlling it. For equipment with raised components, the procedure must specify: the component to be blocked, the blocking material to be used, the blocking point, the sequence of blocking installation, and the verification step before entry is authorised

The most common cause of blocking-related fatalities is the decision that a task is too quick or too minor to justify blocking. OSHA 1910.147 has no exception for short-duration tasks — the hazard exists regardless of how long the worker is in the danger zone. A hydraulic system can fail in less than a second. One second is all that is needed for a crushing fatality

Many LOTO procedures correctly address electrical, pneumatic, and hydraulic energy but omit gravitational energy because the raised component “seems stable.” Every elevated component — dump truck bed, press ram, machine table, crane hook block, dozer blade, excavator arm — stores gravitational energy that is released instantaneously if the supporting system fails. Identify every one

OSHA 1910.217(d)(9)(iv): a die block must be used to prevent ram movement whenever workers place hands in the point of operation. The die block must be specifically designed for the press — not improvised wooden blocks. It must be positively seated and visually confirmed in place before any hand entry. This requirement has no exception for “small” presses or brief die adjustments

OSHA 1910.147(c)(7): authorised employees must be trained in the energy control procedure. For gravitational energy, this means training in blocking: which materials are approved, how to calculate load per stack, correct placement points, how to build and verify a cribbing stack, and the two-person verification requirement. Training must be documented with date, content, and worker signature

OSHA 1910.147 distinguishes between authorised employees (who apply energy control) and affected employees (who work in the area). Only authorised employees may place and verify blocking. An untrained helper placing blocking because the authorised worker is busy is a serious procedural violation and a leading cause of blocking failures

A blocking inventory tells you what you have, its condition, and its rated capacity. Without an inventory, workers use whatever is available — including deteriorated or unapproved materials. Quarterly inspection should check for cracks, splits, crushing, rot, oil saturation, and deformation. Colour-code blocks by quarter inspection with paint on the ends — a red-tagged block is out of service

Removing blocking is as hazardous as installing it. Workers must not re-enter the zone until the load has been lowered and is safely at rest. The removal sequence must be the reverse of the installation sequence. No part of the load should be allowed to drop suddenly — use the hydraulic system to lower the load in a controlled manner before removing each blocking element

Prior blocking failures are the strongest predictor of future fatalities. The most common pattern is a near-miss that is not investigated or corrected — the same improvised blocking or wrong placement point is used again until the next incident is fatal. Every blocking failure, however minor, must be investigated for root cause and the procedure corrected before work resumes