How can I perform my Maghrib and Isha prayers on time, given the difficulty of maintaining wudu after Asr prayer due to the nature of my work?

A Muslim must perform every prayer at its appointed time, unless there is an excuse such as sleep or forgetfulness. Combining prayers is not permissible except for a valid reason. The Hanbalis are of the view that it is permissible to combine prayers for any excuse or harm that would permit missing Friday prayer and congregational prayer. This opinion may be adopted when needed, provided that it does not become a habit.

If Maghrib prayer overtakes you at your workplace, pray it there, unless you know that you will reach home before its time expires and will be able to perform it. Otherwise, you must pray it at work or on the way before its time expires. It is not permissible to combine it with Isha prayer except out of necessity or unusual hardship, provided that it does not become a habit.