A drill pipe is a high-strength steel pipe used in drilling. Depending on the drilling method and purpose of drilling, pipes come in different thickness and lengths, with the most common lengths being 3-10 meters. Drill pipes are joined together one by one as the drill progresses deeper into the bedrock. Together, the pipes form a drill string, which can extend several kilometers down into the ground. Each drill pipe consists of three parts welded together, a central portion and two end pieces. The end piece contains either a male ("pin") or a female ("box") thread, which permits interconnection of two drill pipes. The entire drill string is subjected to extremely high loads during drilling, and the thread is always the most critical part in each pipe. If for any reason the male and female thread do not fit exactly into each other, the thread will most probably break and you will lose your entire drill string.    

Size		Nominal mass Lb/ft	Calculated weight type		Wall thickness
in.	mm		lb/ft	kg/m	in.	mm
2 3/8	60.3	6.65	6.26	9.32	0.28	7.11
2 7/8	73	10.4	9.72	14.48	0.362	9.19
3 1/2	88.9	9.5	8.81	13.12	0.254	6.45
3 1/2	88.9	13.3	12.31	18.34	0.368	9.35
3 1/2	88.9	15.5	14.63	21.79	0.449	11.4
3 1/2	88.9	15.5	14.63	21.79	0.449	11.4
4	101.6	14	12.93	19.26	0.33	8.38
4 1/2	114.3	13.75	12.24	18.23	0.271	6.88
4 1/2	114.3	16.6	14.98	22.31	0.337	8.56
4 1/2	114.3	20	18.69	27.84	0.43	10.92
5	127	16.25	14.87	22.15	0.296	7.52
5	127	19.5	17.93	26.71	0.362	9.19
5	127	19.5	17.93	26.71	0.362	9.19
5	127	25.6	24.03	35.79	0.5	12.7
5	127	25.6	24.03	35.79	0.5	12.7
5 1/2	139.7	21.90	19.81	29.51	0.361	9.17
5 1/2	139.7	24.70	22.54	33.57	0.415	10.54