Original oil and gas trade magazine vintage ad for OIL CENTER TOOL COMPANY of Houston, TX. Service Unlimited. Oil Center Tool Company maintains the largest service organization in the field to help you set and service wellhead assemblies. Unique 1955 old oilfield petroleum industry supply magazine advertisement. O-C-T. On the reverse side is an ad for MIDWEST PIPING COMPANY, INC. of St. Louis, MO. Better Piping at a Better Price by Using Midwest Reducing Elbows. The Midwest Reducing Elbow offers important advantages in both piping design and piping cost. Unique 1955 old oilfield petroleum industry equipment magazine advertisement. Approximate size 9 x 12 inches.