SPECIFICATION FOR ROTARY DRILL STEM ELEMENTS 7

Add the following new Clause 12.

12 Stabilizers

12.1 General

This Clause applies to String Stabilizers and Near-bit Stabilizers, with either Integral-Body or Welded-Blade construction. The important dimensions of stabilizers are defined in Figure 12.

12.2 Definitions

12.2.1

stabilizer (blade) diameter

diameter at largest cross section

12.2.2

wrap angle

total angular extent of full blade diameter, summed across all blades

12.2.3

crown length

axial extent of full blade diameter (except as noted in Figure 15 for watermelon profile) 12.2.4 neck

region at upper and lower end of stabilizer containing connections 12.2.5 blade

enlarged region intended to make contact with the borehole 12.2.6 core

the continuous member of a welded-blade stabilizer 12.2.7

integral-blade stabilizer

stabilizer made from single piece of material 12.2.8

welded-blade stabilizer

stabilizer made from welding blades to a core

8 ADDENDUM 3 TO ANSI/API SPECIFICATION 7-1/ISO 10424-1

Key

1 + 2 + 3 Wrap angle 4 Blade diameter 5 Blade width 6 Inside diameter 7 Blade taper angle 8 Crown length 9 Upper neck length 10 Lower neck length 11 Overall length 12 Neck diameter 13 Radius, 25 mm (1 in.) minimum, 2 places 14 Marking recess

Figure 12 — Measurement Definitions for Stabilizers

12.3 Material requirements

12.3.1 General

Stabilizers may be made from standard steel or non-magnetic stainless steel. Standard steel shall be used unless non-magnetic material is specified. Integral-body stabilizers or the core of welded-blade stabilizers made from standard steel shall be quenched and tempered full-length. 12.3.2 Neck regions

12.3.2.1 Tensile requirements

The neck regions of an integral stabilizer, and the core of a welded-blade stabilizer shall have tensile properties equal to those of drill collars of the same size, as detailed in Table 17 (Table A.17) or Table 18 (Table A.18) of this specification. 12.3.2.2 Impact energy requirements

The neck regions shall also meet the impact energy requirement of Sub-clauses 8.2.1.3 or 8.3.3 of this specification.

SPECIFICATION FOR ROTARY DRILL STEM ELEMENTS 9

Testing of standard steel stabilizers is required on each heat per heat treatment lot. 12.3.2.3 Special testing requirements of integral stabilizers

For an integral-blade stabilizer, the tensile and impact specimens shall be taken from a prolongation of either neck, with the center of the specimen at least 100 mm (4 in.) from a free end, and at least 25 mm (1 in.) below the finished surface of the neck as shown in Figure 13. The prolongation shall be the same diameter as the neck at the time of heat treatment. The uniform region shall extend for at least 400 mm (16 in.) from each end of the finished stabilizer, or to within 25 mm (1 in.) of the stabilizer blades, whichever is less, as shown in Figure 13. The extent of the area of controlled properties shall be verified by Brinell hardness testing, with a minimum hardness of 285 HBW.

When standard steel material is heat-treated as a forging or bar, without knowledge of the final neck diameter, the sampling location shall be determined by the largest diameter of the forging, or the diameter of the bar. In all cases, the radius of the sample location shall be reported.

Table 32 — Sampling requirements

Maximum Diameter of forging or bar

< 188 189 to 245 248 to 508

All dimensions are in millimeters

Radius of Sampling in neck region

35 57 76

>508 89 Key

1, 2 Zone of uniform hot working heat treatment or warm forging 3 Distance from end of forging or bar for mechanical sample 4 Depth below surface of finished neck for mechanical sampling 5 Radius of sampling for forging or raw bar 6 Prolongation

Figure 13 — Sampling locations

12.3.2.4 Traceability

The manufacturer shall establish and follow procedures for maintaining material identity. The methods of maintaining identity shall be at the option of the manufacturer. These procedures shall provide means for tracing the stabilizer body to the relevant heat, chemical analysis report, and specified mechanical test results.

10 ADDENDUM 3 TO ANSI/API SPECIFICATION 7-1/ISO 10424-1

12.3.3 Body regions

An integral-blade stabilizer shall be machined from a single piece of material. The core and necks of a welded-blade stabilizer shall be machined from a single piece of material. The material shall be inspected for defects according to Clause 11 of this specification and shall meet the acceptance criteria as defined therein. Mechanical testing shall only be required for the neck region as defined above.

12.4 Blade Welding

For welded-blade stabilizers, there shall be a documented welding procedure (WPS and PQR) for the welding of blades to the stabilizer core, and welders or welding machines shall have documented qualification (WQR) to this procedure. The welds shall be inspected using a documented procedure of Non-Destructive Evaluation.

NOTE Transverse welding at the ends of blades is not recommended.

12.5 Abrasion protection

The crown surface of the stabilizer shall be provided with protection against abrasion. The protection method is optional to the manufacturer unless specified by the purchaser and is outside the scope of this standard. However, a documented procedure for applying this protection shall exist (WPS for welded hard-facing), and welders or welding machines shall have documented qualification (WQR) to this procedure.

12.6 Dimensional requirements

The following dimensional requirements apply to all stabilizers covered by this standard. 12.6.1 Neck length

The length of upper and lower necks shall be as indicated in Table 33 (Table A.33)

Table 33 — Neck lengths

Location Upper Neck

Lower Neck, String stabilizer Lower Neck, Near-bit stabilizer

All dimensions in millimeters

Minimum lengths

760 600 450

12.6.2 Neck diameters

Upper and lower neck diameter shall be as described in Table 34 (Table A.34). Tolerances shall be the same as those defined for drill collars in Table 15 (A.15)