API Standards for Manufacturing and API Casing Chart

API Standards For Rock Bits And PDC Bits

While in-house engineers decide the various individual differences of pdc bits and tricones, API standards enable drilling professionals the world over to communicate clearly.  All major drill bit manufacturers operate within strict plus and minus tolerances as set forth by the American Petroleum Institute.  API certified casing will be within the drift on the below API Casing Chart.

These standards, known as API Standards, are part of the backbone of the drilling industry.  All reputable PDC and tricone manufacturers follow these guidelines.

The American Petroleum Institute maintains more than 500 standards and recommended practices.  It also represents the oil and gas industry to the public, Congress, state governments, and media.

American Petroleum Institute Standards for PDC and Rock Bit Tolerances

Bit Size (In.)	O.D. Tolerance (In.)
6 3/4" and smaller	-0.015 to +0.00 PDC	-0.0 to +1/32 Rock Bit
6 25/32" to 9"	-0.020 to +0.00 PDC	-0.0 to +1/32 Rock Bit
9 1/32" to 13 3/4"	-0.030 to +0.00 PDC	-0.0 to +1/32 Rock Bit
13 25/32" to 17 1/2"	-0.045 to +0.00 PDC	-0.0 to +1/16 Rock Bit
17 17/32" and larger	-0.063 to +0.00 PDC	-0.0 to +3/32 Rock Bit

Use either a “go” gauge or a “no go” gauge to gauge PDC bits.

Use a “no go”gauge to ensure a bit is not smaller than allowed.  As its name implies, it should not go or slip down the entire length of the bit.  A “go gauge ensures a bit is not larger than allowed and should slip down the entire bit.

3 1/2" to 4 1/2" drill bits	5 5/8" to 7 3/8" drill bits
4 5/8" to 5 1/2" drill bits	2 3/8" API Reg. pin
5 5/8" to 7 3/8" drill bits	2 7/8" API Reg. pin

Number of Nozzles
Nozzle Size	1	2	3	4	5	6	7	8
7	0.0376	0.0752	0.1127	0.1503	0.1877	0.2255	0.2631	0.3007
8	0.0491	0.0982	0.1473	0.1963	0.2454	0.2945	0.3435	0.3927
9	0.0621	0.1242	0.1864	0.2485	0.3106	0.3728	0.4249	0.497
10	0.0767	0.1534	0.2301	0.306	0.3835	0.4602	0.5369	0.6136
11	0.0928	0.1856	0.2784	0.3712	0.464	0.5568	0.6496	0.7424
12	0.1104	0.2209	0.3313	0.4418	0.5522	0.6627	0.7731	0.8836
13	0.1296	0.2592	0.3889	0.5185	0.6481	0.7777	0.9073	1.037
14	0.1503	0.3007	0.451	0.6013	0.7517	0.902	1.0523	1.2026
15	0.1726	0.3451	0.5177	0.6903	0.8629	1.0354	1.208	1.3806
16	0.1963	0.3927	0.589	0.7854	0.9817	1.1781	1.3744	1.5708
18	0.2485	0.497	0.7455	0.994	1.2425	1.491	1.7395	1.988
20	0.3068	0.6136	0.9204	1.2272	1.534	1.8408	2.1476	2.4544
22	0.3712	0.7424	1.1137	1.4849	1.8561	2.2273	2.5986	2.9698

The API Casing Chart below helps determine the drill bit size you need.

API Casing Chart

Number of nozzles
Casing Size OD	Casing Coupling OD	Nominal Weight	Inside Diameter ID	API Drift ID	Roller Cone Bit Size OD		Fixed Cutter Bit Size OD
Inches	Inches	Lbs/ft	Inches	Inches	Inches	Decimal	Inches	Decimal
4 1/2	5	9.5	4.09	3.965	3 7/8	3.875	3 7/8	3.875
4.5	5	10.5	4.052	3.927	3 7/8	3.875	3 7/8	3.875
	5	11.6	4	3.875	3 7/8	3.875	3 7/8	3.875
	5	13.5	3.92	3.795	3 3/4	3.75	3 3/4	3.75
5	5.563	11.5	4.56	4.435	4 3/8	4.375	4 3/4	4.375
5	5.563	13	4.494	4.369	4 1/4	4.25	4 1/4	4.25
	5.563	15	4.408	4.283	4 1/4	4.25	4 1/4	4.375
	5.563	18	4.276	4.151	4 1/8	4.125	4 1/8	4.375
5 1/2	6.05	14	5.012	4.887	4 5/8	4.75	4 5/8	4.75
5.5	6.05	15.5	4.95	4.825	4 5/8	4.75	4 5/8	4.75
	6.05	17	4.892	4.767	4 5/8	4.75	4 5/8	4.75
	6.05	20	4.778	4.653	4 1/2	4.5	4 1/2	4.5
	6.05	23	4.67	4.545	4 1/2	4.5	4 1/2	4.5
6 5/8	7.39	20	6.049	5.924	5 7/8	5.875	5 7/8	5.875
6.625	7.39	24	5.921	5.796	4 3/4	4.75	4 3/4	4.75
	7.39	28	5.791	5.666	4 3/4	4.75	4 3/4	4.75
	7.39	32	5.675	5.55	4 3/4	4.75	4 3/4	4.75
7	7.656	17	6.538	6.413	6 1/4	6.25	6 1/4	6.25
7	7.656	20	6.456	6.331	6 1/4	6.25	6 1/4	6.25
	7.656	23	6.366	6.241	6 1/8	6.125	6 1/8	6.125
	7.656	26	6.276	6.151	6 1/8	6.125	6 1/8	6.125
	7.656	29	6.184	6.059	6	6	6	6
	7.656	32	6.094	5.969	5 7/8	5.875	5 7/8	5.875
	7.656	35	6.004	5.879	5 7/8	5.875	5 7/8	5.875
	7.656	38	5.92	5.795	4 3/4	4.75	4 3/4	4.75
7 5/8	8.5	20	7.125	7	6 3/4	6.75	6 3/4	6.75
7.625	8.5	24	7.025	6.9	6 3/4	6.75	6 3/4	6.75
	8.5	26.4	6.969	6.844	6 3/4	6.75	6 3/4	6.75
	8.5	29.7	6.875	6.75	6 3/4	6.75	6 3/4	6.75
	8.5	33.7	6.765	6.64	6 1/2	6.5	6 1/2	6.5
	8.5	39	6.625	6.5	6 1/2	6.5	6 1/2	6.5
8 5/8	9.625	24	8.097	7.972	7 7/8	7.875	7 7/8	7.875
8.625	9.625	28	8.017	7.892	7 7/8	7.875	7 7/8	7.875
	9.625	32	7.921	7.796	6 3/4	6.75	6 3/4	6.75
	9.625	36	7.825	7.7	6 3/4	6.75	6 3/4	6.75
	9.625	40	7.725	7.6	6 3/4	6.75	6 3/4	6.75
	9.625	44	7.625	7.5	6 3/4	6.75	6 3/4	6.75
	9.625	49	7.511	7.386	6 3/4	6.75	6 3/4	6.75
9 5/8	10.625	29.3	9.063	8.907	8 3/4	8.75	8 3/4	8.75
9.625	10.625	32.3	9.001	8.845	8 3/4	8.75	8 3/4	8.75
	10.625	36	8.921	8.765	8 3/4	8.75	8 3/4	8.75
	10.625	40	8.835	8.679	8 1/2	8.5	8 1/2	8.5
	10.625	43.5	8.755	8.599	8 1/2	8.5	8 1/2	8.5
	10.625	47	8.681	8.525	8 1/2	8.5	8 1/2	8.5
	10.625	53.5	8.535	8.379	8 3/8	8.375	8 3/8	8.375
10 3/4	11.75	32.75	10.192	10.036	9 7/8	9.875	9 7/8	9.875
10.75	11.75	40.5	10.05	9.984	9 7/8	9.875	9 7/8	9.875
	11.75	45.5	9.95	9.794	9 1/2	9.5	9 1/2	9.5
	11.75	51	9.85	9.694	9 1/2	9.5	9 1/2	9.5
	11.75	55.5	9.76	9.604	9 1/2	9.5	9 1/2	9.5
	11.75	60.7	9.66	9.504	9 1/2	9.5	9 1/2	9.5
	11.75	65.7	9.56	9.404	8 3/4	8.75	8 3/4	8.75
11 3/4	12.75	42	11.084	10.928	10 5/8	10.625	10 5/8	10.625
11.75	12.75	47	11	10.844	10 5/8	10.625	10 5/8	10.625
	12.75	54	10.88	10.724	10 5/8	10.625	10 5/8	10.625
	12.75	60	10.772	10.616	9 7/8	9.875	9 7/8	9.875
13 3/8	14.375	48	12.715	12.559	12 1/4	12.25	12 1/4	12.25
13.375	14.375	54.5	12.615	12.459	12 1/4	12.25	12 1/4	12.25
	14.375	61	12.515	12.359	12 1/4	12.25	12 1/4	12.25
	14.375	68	12.415	12.259	12 1/4	12.25	12 1/4	12.25
	14.375	72	12.347	12.191	11	11	10 5/8	10.625
16	17	65	15.25	15.062	14 3/4	14.75	14 3/4	14.75
16	17	75	15.124	14.936	14 3/4	14.75	14 3/4	14.75
	17	84	15.01	14.822	14 3/4	14.75	14 3/4	14.75
18 5/8	20	87.5	17.755	17.567	17 1/2	17.5	17 1/2	17.5
18.625	-	-	-	-	-	-	-	-
20	21	94	19.124	18.936	17 1/2	17.5	17 1/2	17.5
20	21	106.5	19	18.812	17 1/2	17.5	17 1/2	17.5
	21	133	18.73	18.542	17 1/2	17.5	17 1/2	17.5
	21	169	18.376	18.188	17 1/2	17.5	17 1/2	17.5