In short we can say that the riser is a tube that connects a floating offshore production structure, or a drilling platform, an undersea system for productive purposes, like drilling, production, and export, or for drilling, completion and workover.
Like any equipment when some type of damage, the risers need constant repairs to return to work effectively. Among the benefits of maintaining the riser are: avoid damage to the riser increase, making it totally dead; ensure the operating conditions which the manufacturer designed riser; avoid the risk of personal accident and either; reduces damage to other equipment that run along with the riser on the platform.
In addition, the riser is used in much of the drilling of a well. Not having enough riser joints on the platform means that much of the drilling will not occur, that's why he's so vital in the offshore world.
There are two types of maintenance of risers: the preventive and the corrective. In the first you do an estimate of when a piece will stop working, and replaces it with a new one to avoid any kinds of problems. Already the corrective maintenance is made when any part of the riser has given problem, which paralyzes the equipment causing milhões are lost in that time.
In Brazil, many companies perform the riser repair services, both preventive as the correction.