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We present the orbital X-ray modulation study of three high mass X- raybinary systems, IGR J18027-2016, IGR J18483-0311 and IGR J16318-4848 using dataobtained with RXTE-ASM, Swift-BAT and INTEGRAL-ISGRI. Using the long term lightcurves of the eclipsing HMXB IGR J18027-2016, obtained with Swift-BAT in theenergy range 15-50 keV and INTEGRAL-ISGRI in the energy range 22-40 keV, wehave determined three new mid eclipse times. The newly determined mid eclipsetimes together with the known values were used to derive an accurate value ofthe orbital period of 4.5693(4) d at MJD 52168 and an upper limit of3.9(1.2)x10^-7 d d^-1 on the period derivative. We have also accuratelydetermined an orbital period of 18.5482(88) d for the intermediate system IGRJ18483-0311, which displays an unusual behaviour and shares many propertieswith the known SFXTs and persistent supergiant systems. This is a transientsource and the outbursts occur intermittently at intervals of 18.55 d.Similarly, in the third supergiant system, IGR J16318-4848, we have found thatthe outbursts are separated by intervals of 80 d or its multiples, suggesting apossible orbital period.

Orbital X-ray modulation study of three Supergiant HMXBs