Defence Standard (Def Stan) 02-304 Part 4 specifies the requirements for:

Assessment of the rectification and repairs necessary to restore distorted, worn or corroded main propulsion shafts, couplings and sleeves to a serviceable condition; 

Performance of such treatment and repairs; 

Post-repair treatment and inspection. Shaft materials include carbon steel, stainless steel and non-ferrous alloys.

Individual requirements or limitations relating to shafts for specific vessels are included.

Rectification and repair techniques considered include:

Grinding; 

Machining; 

Welding; 

Metal spraying;

Straightening;

Plastic coating.

Post-repair operations include heat treatment, surface treatment and inspection. Acceptance standards are defined.

The requirement to raise and maintain a repair history document for each main propulsion shaft is stated.