Cranes & pressure equipment: follow the regs
Published in: New Zealand Forest Industries Magazine
Date: 2/1/2003
By: Dobbie, Jim
Most timber processing plants use pressure equipment and/or cranes in their production process. However there have been several cases recently of sawmills and process plants buying or fabricating such items only to discover they cannot be legally used for the intended application.
Examples include:
* A workshop overhead travelling crane skilfully fabricated but scrapped due to incorrect design and unknown steel quality.
* An imported processing vessel that was scrapped on arrival, resulting in project delays and the cost of a replacement vessel.
* A large new process crane with a certified useful life of only three years. Upgrading was needed to achieve a more realistic 15-year life.
Cranes and pressure vessels are very expensive plant items. All of these situations could have been easily avoided if the purchaser, supplier or fabricator had followed the regulations that now apply to all cranes and pressure equipment (including piping).
Owners and operators need to be aware of the requirements for operating, purchasing and maintaining equipment covered by these rules. Under the Health and Safety in Employment Act 0992) there are obligations to ensure pressure equipment and cranes are fit for the purpose and used safely. In the past, generally acceptable practices established by the Marine Division of the Department of Transport were followed for pressure equipment and cranes. OSH also issued various Engineering Safety Notices to record acceptable procedures and areas of concern.
In 1999 a new law was passed to define the requirements for pressure equipment and cranes, the Health and Safety in Employment (Pressure Equipment, Cranes and Passenger Ropeways) Regulations 1999, otherwise known as the PECPR Regulations. As well as defining pressure equipment and cranes, the regulations require that the design, materials, fabrication, testing, operation, inspection and repair are to recognised safe standards. Depending on the risks involved, independent verification of design, fabrication, testing and in service inspections may be required.
OSH introduced Codes of Practice for Boilers, Pressure Equipment and Cranes and these describe the typical methods of complying with the PECPR regulations.
Clause 10 applies to new and existing equipment and requires owners to maintain the equipment in a safe condition and operate it safely within the limits that it was designed to. Owners need documents indicating the equipment has been designed and is operating within the limits of the design. Regular maintenance and inspections of equipment needs to be carried out and documented.
Pressure equipment
Pressure vessels are tanks and containers which hold, store, process or transport gases or liquids at pressures exceeding 50kPa (7.2psi) or steam at any pressure above atmospheric pressure and above 100[degrees]C. Pressure piping has a similar definition to that of pressure vessels. The PECPR Regulations require all pressure piping, pressure vessels and boilers to be designed to a recognised standard. Typical pressure equipment found on timber processing sites includes:
* Boilers–steam, hot water and thermal oil.
* Compressed air receivers.
* Hydraulic system accumulators.
* Timber treatment vessels.
* Pressurised hot water piping and equipment for timber drying.
* Steam piping and coils for timber drying.
(Schedule 2 to the PECPR Regulations has a list of excluded items. Note that water reticulation systems are not excluded at this stage, although this has been requested.)
Equipment covered by the PECPR Regulations must be designed and then design-verified in accordance with an appropriate standard. Two experienced people are therefore involved with the design. Typically, pressure equipment and crane design is carried out by a professional qualified mechanical engineer.
Design verification requirements vary with the hazard of the equipment. Host equipment requires the design to be verified by an independent inspection body that employs professional engineers who have OSH recognition as being competent in their field (eg cranes, pressure piping). A few design companies have OSH recognised design verifiers on their staff and can carry out both the design and design verification for certain hazard levels.
During fabrication, inspection is required to ensure that the dimensions, materials and quality of work matches the design. Independent inspectors are often required for these inspections.
Cranes
Every lifting device that can move a load vertically and horizontally by a powered means is covered by the PECPR Regulations. A Hiab on the back of a truck is a crane. A monorail with an electric hoist and a manual trolley is not covered. If the trolley is motorised then the PECPR Regulations apply.
Typical uses of cranes on processing sites are:
* Gantry cranes for handling timber packets.
* Cranes used for stacking logging trailers.
* Gantry cranes in workshops.
* Powered monorails for timber packet handling.
* Log grapples acting as a crane.
For a gantry crane, a professional mechanical engineer will typically design the parts that move with a professional structural engineer designing the building structure that supports it. Design verification is also required for cranes.
Plant managers
Managers and supervisors at sawmills and industrial plants are likely to have operating procedures for existing boilers, pressure vessels and cranes. Care is needed both when buying new equipment and when relocating or modifying existing equipment to ensure compliance with the PECPR Regulations.
Purchasing
In addition to describing the duty requirement of the crane or pressure vessel it is important to insist the new equipment will comply to the PECPR Regulations and that verification certification for design and inspection certificates for construction are provided.
It is preferable to further tighten these requirements to a design and construction standard that is commonly used in New Zealand and recognised by the PECPR Regulations.
Purchase orders and tender documents should state that the design, materials, fabrication and testing must comply to an appropriate standard.
ASME B31.1 for steam or hazardous gas piping, ASME B31.3 for liquids and process piping, AS4041 for compressed air and water piping, ASME VIII, NZS/PD 5500 or AS1210 for pressure vessels (eg, an air receiver) and AS1418 or BS466 and BS2573 for cranes are the most frequently used standards with listed components and materials available in New Zealand. However specific installations should be reviewed to confirm the appropriateness of the standard for the application. There are other acceptable codes that equipment suppliers may use but these must be confirmed for compliance to New Zealand regulations.
The above items apply to new, second-hand and imported items. If you cannot get the history of second-hand pressure vessels or cranes, consider the methods and costs that may be required to verify the design and construction. When relocating plant covered by PECPR Regulations it will be necessary to confirm that the equipment is still operating within the design limits. Typically a professional engineer should be employed to confirm the design limits are still applicable for the new application.
Repairs
Repairs need to be carried out with materials listed in the standards and by tradesmen qualified to the standards. The repairs must not change the original design. Depending on the hazard rating, independent inspections (eg, x-ray of welds) may be needed in addition to normal pressure or loading tests.
Alterations that change the design will require a professional engineer to be involved and maybe an independent design verifier depending on the hazard rating. A change to the pressure, temperature, geometry, or supports is classified as an alteration.
Operation
Cranes and pressure equipment generally have Safe Working Loads or Maximum Pressure and Temperature Ratings marked on them. They must be operated within these limits.
In-service inspections
All cranes and pressure equipment must be inspected when first commissioned. The date of the next inspection is then determined.
Detailed inspection reports should be kept and can be used to vary the frequency of inspections.
Depending on the hazard rating the PECPR Regulations 1999 allow the owner’s staff to carry out some inspections. Most inspections will need to be carried out by approved organisations providing in-service and fabrication inspections. These organisations are familiar with the applicable standard eg “AS/NZS 3788 Pressure Equipment, In-service Inspections” and know the critical areas to check.
Documentation
All cranes, pressure vessels and pressure pipes should have files containing original drawings, design verification and inspection certificates and a history of alterations, repairs and in service inspections.
For planning purposes it is suggested that a file and spreadsheet is created identifying all the pressure equipment and cranes on a site. This should monitor their location, rating, next inspection date and reference where the historic records are kept.
Declaration of interest:
Dobbie Engineers is a firm of consulting mechanical engineers based in Rotorua and Auckland. Pressure piping, pressure vessel and crane are design core activities of the company. The assistance of the Engineering Safety staff of the Department of Labour, Wellington in reviewing this article is acknowledged.
Typical inspection frequencies
Item Frequency & Inspection Type
Boilers, treatment cylinders 1 year internal and external
Air receivers internal and external 1 year after
commissioning, then 2 years
external, 4 years internal
Pressure piping 5 years external, 12 years internal
Cranes 1 year COPYRIGHT 2003 Profile Publishing Ltd.