'positioned parallel to' is correct and can be used in written English.
You can use it when describing two objects or directions that are at the same distance from each other and running in the same direction. For example, "The two buildings are positioned parallel to each other and separated by a narrow street."
The Hg lamp was positioned parallel to the quartz tube.
As shown in Fig. 3a, the monitor was positioned parallel to the ground.
The shading device is a flat panel positioned parallel to the window and inclined by its horizontal axis.
Deposition with thickness of the order of 1 μm also occurred, but was considerably thinner for samples positioned parallel to the plasma stream.
In this way, the electrode was positioned parallel to the muscle fibers and positioned more or less superficially in comparison with the frontoparietal suture.
The chisel was positioned parallel to the vestibular surface of the tooth and bracket interface to allow force transmission in the occlusal-gingival direction.
long positioned parallel (at 0°) to the longitudinal axis of the beam on bottom and sides of the beam.
The instrument is played in a seated position, the body of the instrument held on the lap in a nearly vertical position parallel to the torso.
Filmed from a prosaic position parallel to the bar's back wall, Norton's punch is a flat, undramatic blow, and its unadorned impact allows Pitt, never the subtlest of performers, to bring out all the pain.
He had planned to make the earth station his weekend home, and he tweaked the dish's position from a right angle to a position parallel to the ground so that it looks like it is levitating by the structure.
In Tenerife, he has built a waterfront concert hall that looks like a shell topped with a ram's horn; in Buenos Aires, he has created a cable-strung footbridge that, spectacularly, pivots from its transverse position to a position parallel to the bank, to permit the passage of water traffic.
