IS Code 3696: Ladder Safety Guidelines
IS Code 3696 speaks about ladders to be provided on scaffolds. Portable ladders are not recommended for flights above 4 meters. They should be placed at an angle of approximately 75° from the horizontal. Both the top and bottom should be secured to prevent displacement, and the ladder rails should be extended at least 1 meter above the top landing.
Fixed ladders should be provided for flights above 4 meters. Fixed ladders should have landings of a minimum 600 mm extent at intervals not greater than 6 meters. The width of the ladder shall not be less than 300 mm, and the rungs shall be spaced not more than 300 mm apart.
In your case, the ladders should be attached to the boiler. They can be straight, with both the bottom and top secured.
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