I solved problem by manually setting 'boot' flag to 'on' for this flash drive
with GNU Parted:
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rob@Rob:~/Загрузки$ sudo parted /dev/sdb
GNU Parted 3.2
Using /dev/sdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print
Model: JetFlash Transcend 16GB (scsi)
Disk /dev/sdb: 15,7GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 
 
Number  Start   End    Size   Type     File system  Flags
 1      32,8kB  717MB  717MB  primary
 
(parted) set 1 boot on
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After that parted would show 'boot' flag on same flash drive:
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Number  Start   End    Size   Type     File system  Flags
 1      32,8kB  717MB  717MB  primary               boot
---------------------------------------------------------
I was finally able to boot from it and perform installation on target computer.
This computer has pretty old hardware, so maybe the reason is older versions of
BIOS need this flag to tell if device is bootable?
The rest of target computers will probably be no better in this regard.
 
Thanks to Thomas Lange and Robert Markula for help.
Im now writing some brief description of my company's project for which i
consider using FAI.
Should i post it under this topic?

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