What happened? On 11th January at 00:00 hrs crew were working on N/up BOP. Afterwards, the crew started to connect the flow line extension to bell nipple using rig floor winch and MEWP to align the flow line. Floorman (1) placed his hand on flow line to have a better and clear view while aligning the flow line extension. Meanwhile without prior notice or given instructions, floorman (2) (the winch operator) started winching up the flow line, the floorman (1) hand was caught in between flow line and BOP winch beam, resulting in crush injury to the floorman (1) right hand thumb. Held TOFS, floorman (1) was sent to rig medic for evaluation and referred to hospital for further medical evaluation as per ARA doctor advice. Why it happened/Finding : COW under a PTW were in place, along with using hand-held radios. No proper tools or engineering design enabling safe and effective handling of the flow line manually without causing hand injuries. Poor situational awareness - Floorman placed his hand in line of fire on flow line while overseeing the flow line alignment. Task was taking place at midnight. Sufficient lighting was available at the subbase and surrounding areas.