Tender For corrigendum : supply of 4" - 13-3/8" hydraulic casing tong with hydraulic power unit , 2-3/8" - 4-1/2" hydraulic tubing tong with hydraulic power unit , 2-3/8" - 4-1/2" hydraulic tubing tong without hydraulic power unit , 4" - 13-3/8" hydraulic casing tong without hydraulic power unit , 20" hydraulic casing tong without hydraulic power unit