R25	R32	R32	R38	R51	R63	R76	R89	R103
Max Diameter over Threads (mm)	25	32	32	38	51	63	76	89	103
Internal Diameter (mm)	13	20	15	15	28	43	56	69	83
Effective Cross Sectional Area of Bar (mm2)	325	447	560	780	1200	1660	2080	2450	2920
Ultimate Strength (kN)	200	280	405	530	838	1100	1380	1600	1980
Tensile Yield Strength (kN)	160	230	335	440	693	909	1140	1280	1636
Steel Grade Yld/Ult (N/mm2)	515	515	598	564	577	547	548	522	560
E Modulus (N/mm2)	200,000	190,000	190,000	190,000	180,000	180,000	180,000	170,000	170,000
Weight (kg/m)	2.30	3.51	4.40	6.12	9.50	13.32	16.33	19.24	22.93
Thread Type	R	R	R	R	R	R	R	R	R
Steel Quality	S355	Fe55	Fe55	Fe55	28MnB5	28MnB5	S355	S355	S355
Bar Lengths (m)	3.0m, 4.0m

Typical Hollow Thread Bar                                            Typical Thread Bar Couplers & Termination Accessories 

ROMTECH’s Hollow Bar system is a continuously threaded left handed steel bar which can be drilled and grouted into loose, unstable and collapsing ground. The steel is a hollow configuration to allow for simultaneous drilling and grouting, a technique designed for eliminating the need for pre-casing, therefore increasing the installation rate.

Produced from hollow steel tubular raw material, the bar is cold rolled into a standard ISO rope thread during which the formation of steel is enhanced, providing the yield strength. The rope thread provides an appropriate surface between the bar and the grout, therefore enabling a strong, resilient bond to be created.

ROMTECH Self Drill Hollow Bar provides effective solutions for rock bolting, ground anchoring, micro piling, soil nailing and spiles applications.

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