1. (1) All casing installed, other than plastic casing as set forth in ARM 36.21.641 and 36.21.645, shall be steel, in new or like new condition, being free of pits, breaks, or contamination, and shall meet minimum American Society of Testing Materials (ASTM) A53 specifications for line pipe for the following sizes:
2. (2) All casing having a diameter larger than 20 inches shall have a wall thickness of at least 0.375 inch.

3. (3) Well casing installed in a well greater than a nominal diameter of ten inches, may have a wall thickness of 0.250 inch as long as it otherwise meets ASTM A53 specifications and does not exceed the following depth limitations:

   Table 2 – Diameter and depth limitations.

   Diameter	Maximum Depth
   12 inches	250 feet
   14-16 inches	150 feet
   18-20 inches	100 feet

4. (4) Casings of other specifications may be considered under the provisions of variances ARM 36.21.680.

   Table 1 - Minimum specifications for steel well casing.

   Nominal Size (inches)	Outside Diameter (inches)	Wall Thickness (inches)	Weight Per Foot (pounds)
   2	2.375	0.154	3.56
   2	2.875	0.203	5.79
   3	3.500	0.216	7.58
   3	4.000	0.226	9.11
   4	4.500	0.237	10.79
   5	5.563	0.244	13.70
   6	6.625	0.250	17.02
   8	8.625	0.250	22.36
   10	10.750	0.250	28.04
   12	12.750	0.312	41.45
   14	14.000	0.312	45.68
   16	16.000	0.312	52.27
   18	18.000	0.375	70.59
   20	20.000	0.375	78.60

Authorizing statute(s): 37-43-202(3), MCA

Implementing statute(s): 37-43-202(3), MCA

History: NEW, 1986 MAR p. 1699, Eff. 10/17/86; AMD, 2010 MAR p. 1614, Eff. 7/16/10.