=41.= The following is a sample set of specifications for a steel
head-frame to be built from detailed plans furnished by the mining
company.
This head-frame to be made from drawings to be furnished by the----
Coal Company, and placed on foundations furnished by said company.
=Material.=--Structure to be built throughout of soft structural steel,
net strength 55,000 to 62,000 pounds per square inch; elastic limit
not less than 30,000 pounds per square inch; elongation, 25 per cent.;
bending test, bend flat on itself without fracture.
Builder agrees to guarantee structure to withstand strains specified
on drawings with factor of safety of 10, to provide for possible
overwinding or sticking in shaft.
No steel shall be used less than ¼ inch thick except for lining or
filling vacant places.
=Workmanship.=--The tower to be built in a neat and workman-like
manner. The pitch of the rivets (distance between centers) shall not
exceed 6 inches or sixteen times the thinnest plate, nor be less than
three diameters of the rivets.
The rivets used shall generally be ½ inch, ¾ inch, and ⅞ inch in
diameter.
The distance between edges of any piece and the center of rivet hole
shall not be less than 1¼ inches, except for bars less than 2½ inches
wide; when practicable it shall be at least two diameters of the
rivet. All rivet holes shall be spaced and punched, so that when the
several parts are assembled together a rivet of ¹/₁₆ inch less diameter
than the hole can be entered hot into any hole, without reaming or
drifting. The rivets when driven should fill the holes. The heads must
be rounded; they must be full and neatly made, and be concentric to
the rivet hole, and thoroughly pinch the connecting pieces together.
Field riveting must be reduced to a minimum. All joints and connections
shall be neatly made, the several parts to be brought together without
twists, bends, or open joints.
=Inspection.=--All facilities for inspecting the material and
workmanship shall be given by the builders during the erection of the
head-frame. The company reserves the right to reject any or all parts
not built in accordance with the plans or these specifications. Final
inspection of work 1 month after being in actual service.
=Painting.=--All work, before leaving the shops, shall be thoroughly
cleaned from all loose rust and scale, and be given one good coat of
paint well worked into all joints and open spaces. In riveted ironwork,
the surfaces coming in contact shall each be painted before being
riveted together. Bottoms of bearing plates and any parts that are not
accessible for painting after erection shall have two coats of paint.
After the structure is erected in place, it shall be given one coat of
paint. All recesses that will retain water, or through which water can
enter, must be filled with thick paint or some waterproof cement before
receiving the final painting. The paint shall be a lampblack paint,
mixed with pure linseed oil, or of red lead mixed with raw linseed oil
containing Japan dryer.
=General Clauses.=--The specifications and drawings are intended to
cooperate and to indicate the principal dimensions and requirements
necessary to the complete structure. It being understood that
while some work may be shown in the plans and not described in the
specifications, or vice versa, and some minor details and fastenings
are omitted from both plans and specifications, the work is to be
executed without extra charge therefor, the same as if the minutest
details were set forth in full in both drawings and specifications.
The contractor is to make good any defects of material or workmanship
developing within 1 year after final acceptance.
The contractor shall furnish a location plan and also two copies of the
detail shop drawings for convenience in making future alterations and
repairs.
=Erection.=--The head-frame is to be erected complete, secured to
foundations provided by the---- Company.
Contractor shall furnish all foundation bolts and washers. Iron
stairway with hand rails beside main back bracers and platform with
wooden floor under sheaves, also iron stairs from platform under
sheaves to back sheave pedestal for oiling. Wood furnished by the----
Company.
Price includes all material for completion of work delivered, erected,
and riveted in place and painted.
The---- Company will furnish and place in position the sheaves, with
the shafts and boxes belonging to the same, also the wooden guides.
=Delivery.=--The head-frame to be erected, complete, and secured to
foundations in---- weeks from date of order.