These collars are usually 1/16” less than the Drilling Bit size, and are run to provide maximum stabilization of the Drilling Bottom Hole Assembly (BHA). The shoulders and threads must be lubricated with the correct lubricant (containing 40- 60% powdered metallic zinc or lead). It is very important that proper care is taken when handling D/Cs. The weights that are quoted in Table 2 are the “weight in the air” of the D/Cs. The Drill collar size and weights per foot of a range of DC size are shown in Table 2. Drill Collar Weights & Sizeĭ/Cs are produced in a large range of sizes with various types of joint connections. The bore of the collar is accurately machined to ensure a smooth, balanced rotation. The collars are manufactured from chrome-molybdenum alloy, which is fully heat-treated over the entire length. Drill Collar Lengthĭ/C are normally supplied in Range 2 lengths (30-32 ft). Purchase orders for collars with optional connections should state the outside diameter, bore, length, connection size and style, and bevel diameter. Purchase orders for collars with the improved connections should state the D/C number or size and style, bore, and length. The drill collar sizes listed in Table 1 were adopted in order to provide a full range of DCs with improved connections, as a replacement for the DCs with the various connections specified in previous editions of API Spec If the connections shown in parentheses in column 1 are made with the V-0.038R thread, the connections and D/Cs, are identical with those in the NC style.ĭ/Cs with 8-1/4 and 9-1/2 inches outside diameters are shown with 6-5/8 and 7-5/8 REG connections since there are no NC connections in the recommended bending strength ratio range. The connections shown in parentheses in column 1 are not a part of the D/C number they indicate inter-changeability of D/Cs made with the standard (NC) connections as shown. The second part, consisting of 2 (or 3) digits, indicates the Drill Collar outside diameter in units and tenths of inches.The first part is the connection number in the NC style.The D/C number (column 1) consists of two parts separated by a hyphen. Table 1 : Standard Drill Collar Thread Types
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