Fitting of Q class flat wagons with special bolsters to carry pipes started in 1955. The converted wagons were reclassified QP. There were eventually 43 QP class wagons. The QPS class was created by the conversion of twenty QP class pipe bolster wagons in 1965. These were temporary and had all been reconverted to class QP by 1967.

QPS 3224

After a period where wagons were written off conversion from class QP to class QPS started again and class QP ceased to exist by 1976. A total of 36 wagons became class QPS. At least one of the QPS's seems to have run in its later years with no bolsters (3224)

QPS 4480

1955

2877, 2996, 3204/9, 3217, 3224, 3525/9, 4440/1, 4465, 4480/2/8, 4497, 4897 from Q to QP

1976

1662, 1673, 1722, 2877, 2988, 2994, 3209, 3221, 3492, 4440, 4478, 4488, 4662, 4775, 4779 QP to QPS

1956

3212, 3247, 4472/7/8 From Q to QP

QP 2996, 3529 written off - class QP extinct

1962

1662, 1673, 1722, 2152, 3492, 3642, 4775, 4799, 4805 from Q to QP

Written off QP 2152 to QPS

1965

1662, 1673, 1722, 2877, 2996, 3212, 3247, 3525, 3642, 4440, 4465, 4472/7/8, 4488, 4497, 4775, 4799, 4805, 4897 QP to QPS

1979

QPS 2983, 4472/8, 4799 written off

1662, 2877, 2996, 3212, 3247, 3525, 4465, 4477, 4497, 4799, 4897 QPS to QP

1980

QPS 1722, 2994, 3204, 3221, 4805 written off

1967

690, 2988, 3527 from Q to QP

1981

QPS 3642 written off

1968

4474 from Q to QP

1982

QPS 1673, 3492 written off

1971

QP 4482 written off

1984

QPS 2877, 4662 written off

1972

QP 3223/7, 3247, 3525 written off

1985

QPS 690, 1662, 3209, 3526, 4775 written off

1973

QP 2152, 3217, 3226, 4465, 4497, 4897 written off

1988

QPS 2988 written off

1975

690, 2983, 3204, 3211/2, 3224, 3526, 3642, 4441, 4472/4/7, 4480, 4805 QP to QPS

1990

QPS 2152, 3211, 3224 written off

QP 3527 written off

 QPS 4441 and 4480 unaccounted for.