Use of passive in order to focus action itself, not on who does the action (the agent).
The Present Perfect passive used to talk about events that happened in a period of time that continued from the past up to the present. Time expression not used with present perfect tense because time is unspecified.
have/has + been + past participle
E.g. The topside has been fitted to the spar
The Past Simple passive used with completed actions or actions that took place at a specific time.
was/were + past participle
E.g. The topside was fitted to the spar in 2009.
For more information, see Course Book Language Summary, page 101
Cohesion; by (means of); (in order) to
Method: to explain how we did something
use ‘by’ …-ing / using / by means of
E.g. The spar was secured by fastening it to the seabed with nine cables.
Purpose: to explain why we did something
in order + infinitive / in order to
E.g. The spar was secured (in order) to prevent it from moving around in heavy seas.
