one
cementing unit 1 - step 1 - arrival 02x   Cementing unit 1 - step 4 - finished 01

[1]

cementing 2 before 1x   cementing 2 after 1x

[2]

cementing 2 before 2x   cementing 2 after 2x

[3]

cementing 2 before 3x cementing 2 after 3x

[4]

cementing 2 before 4xy   cementing 2 after 4x

[5]