In the past 20 years rope access has become more and more used as method of access due to its low cost and high speed compared to other access methods like scaffolding or mobile erected work platforms (MEWPS).
At first rope access was seen as a dangerous activity that only a select few could practice. There are now safe systems of rope access like the two ropes system used by IRATA (Industrial Rope Access Trade Association) or SPRAT (Society of Professional Rope Access Technicians).
But can rope access be used safely to access structures that need abrasive blasting?
When blasting high structures there are some factors that need to be taken into account:
- The abrasive jet can cut both the safety and work rope. Especially if one of them is under tension (e.g.: supporting the weight of the technician). To mitigate this, a mobile rope protector can be used on the ropes, just above the technician (one protector for each rope). If a lanyard is used to connect the backup device to the harness of the operator, then this lanyard must be protected accordingly using a rope protector suitable for the blasting operation (e.g.: rubber).
- A suitable backup device should be used, as abrasive blasting generates a lot of dust and certain backup devices that include many moving parts can become stuck and loose some of their functions.
- There is substantial movement from the abrasive jet impinging onto the surface, and this can induce spinning of the technician. To reduce this the ropes can either be tensioned from the ground or sides or anchors and deviations should be installed, in order to permit the technician to be as close to the surface as possible but allowing in the same time the correct blasting distance.
- The blast hose sometimes is heavy or can become heavy (by filling with abrasive in case of a malfunction). A good practice is to use an independent set of ropes for the suspension of the hose.
In the picture above the use of magnetic anchors and tensioned lines can be seen on the blasting works done by AlpAccess for Exxon-Mobil’s Zafiro Producer FPSO off the coast of Malabo Equatorial Guinea).
- Blasting will shorten the life of the ropes as dust particles can penetrate the shell of ropes and cut some of fibers. The abrasive particles can induce wear also in the descenders that use friction to dissipate energy. The reuse of the ropes after a blasting project should be thoroughly assessed.
- Environment regulations. Blasting generates a lot of dust and spent abrasive before engaging in this activity we must ensure that the environmental impact is kept as low as possible and that we respect the local legislation. In some parts of the world you can blast over open water in other parts of the world blasting outside ventilated enclosures is strictly forbidden.
- Rope access should only be conducted by trained and certified personnel following clear procedures. For this IRATA offers a comprehensive code of practice and a training scheme with an impressive track record. The IRATA system has become the rope access system of choice for offshore installations all over the world.
- Furthermore, rope access blasting operations should only be conducted by experienced rope access technicians following a detailed method statement and a specific risk assessment.
- A rescue plan must be in place to allow the transport to safety of an eventually injured rope access technician.
- Blasting being a strenuous activity, it is a good practice to have technicians taking turns to allow rest periods. A minimum team size can consist in three technicians (2 rope access IRATA Level 1/Level 2 blasters and one IRATA level 3 supervisor that can act also as a standby rescue).
In the picture the independent suspension of the blasting hose and tensioning of the working rope, can be seen. The project consisted in the blasting and painting by AlpAccess, of a 50.000 m3, crude oil storage tank, in the Petromidia refinery on the Black sea shore in Romania.
In conclusion, rope access can be used for blasting operations in a safe manner providing that proper planning and safety measures are implemented. Rope access is a versatile access method and can be used on a variety of structures and shapes. It is best suited for blasting of interior of tanks where all the dust generated by the abrasive blasting can be contained and evacuated.
Best results in terms of safety, speed and quality, are obtained by combining rope access with other access methods like scaffolding, suspended decks and MEWP’s ol part of an integrated access solution.
Autor:
Dragos State
General Manager – AlpAccess
• FROSIO Surface treatment inspector level 3
• NACE CIP Level 3
• SSPC PCI Level 3
• IRATA Level 3 supervisor
• SPRAT Level 3 supervisor
• NEBOSH IGC
• NEBOSH IOG
