Overburden Casing System

Concentric Casing System Type1

Type	Casing OD (mm)	Casing Min ID (mm)	Reaming Diameter (mm)	Casing Shoe Min ID (mm)	Pilot Bit Max OD (mm)	DTH Hammer
GL70A-70-89	89	77	98	71	70	GL70A
GL90-85-108	108	94	112	86	85	GL90/GL90-I
GL335-85-108	108	94	114	88	86	GL335
GL335-90-114	114	98	127	91	90	GL335
GL335-100-127	127	114	136	101	100	GL335
GL110-120-146	146	130	156	121	120	GL110
GL4.5-120-146	146	130	156	121	120	GL4.5
GL340-120-146	146	130	156	121	120	GL340
GL350-140-168	168	152	180	142	140	GL350/355/355K
GL350-145-178	178	160	183	146	145	GL350/355/355K
GL350-150-183	183	165	190	152	150	GL350/355/355K
GL360-186-219	219	194	240	187	186	GL360
GL360-194-219	219	194	240	195	194	GL360
GL360-203-219	219	203	240	206	203	GL360
GL380-203-219	219	205	240	206	203	GL380
GL380-203-245	245	232	266	206	203	GL380
GL380-241-273	273	260	305	244	241	GL380
Code annotation of casing reamer bit as bellow
Example： GL350-140-168
GL350(Equal to DHD350)=Hammer type, 140= Pilot Bit Max OD (mm), 168=O.D of casing pipe(mm)