Engineering Sample Specifications

Engineering Sample SpecificationsUse this sample specification to develop or enhance your specification for shop fabricated stainless steel piping systems. This specification is our standard for lightwall piping for low and moderate temperature and pressure applications of water, air, gas, and other services in the process industries. The designer / specifier must determine if this specification is suitable for their unique industry and applications.



1.01: Scope of Work

A. The contractor shall furnish all materials, tools, equipment, transportation, labor, supervision and incidentals required to supply, store, install, clean, and test the shop fabricated stainless steel pipe & fittings as shown on the drawings and as specified herein.

1.02: Description of System (s)

A. Shop fabricated stainless steel piping shall be used for the following applications. [List, table or otherwise describe services, sizes applications, locations, service conditions, etc. and/or refer to pipe schedule.]

1.03: Related Work Not Included in This Section

A. Steel piping is included in Section ( )
B. Concrete work is included in Section ( )
C. Painting is included in Section ( )
D. Pipe hangers & supports are included in Section ( )
E. Valves & appurtenances are included in Section ( )
F. Testing is included in Section ( )

1.04: Qualifications

A. All shop fabricated stainless steel pipe and fittings shall be furnished by a single fabricator who is reputable and qualified and can demonstrate 10 years experience in the fabrication of lightwall stainless steel piping. The pipe and fittings shall be shop fabricated and field installed in accordance with common industry wide practices and methods and shall comply with these specifications. Pipe and fittings shall be as fabricated by Douglas Brothers, Portland, Maine.

1.05 Submittals

A. The contractor shall submit for review and approval piping layouts, schedules, shop fabrication drawings, specifications, catalog cuts and other data necessary to show conformance of the complete piping systems to these specifications. The contractor’s submittal shall include dimensions, fittings, locations of equipment, valves, and appurtenances, joint locations and details, types and locations of supports, coordination with all other work and existing conditions, and all other pertinent technical specifications for the piping systems to be furnished.

B. Shop fabrication spool drawings shall show alloys, diameters, pipe wall thickness, fittings, branches, flanges and other joint preparation details, dimensions, and other appurtenances to be supplied.


2:01: Pipes and Fittings, 3” diameter and larger.

A. Pipes shall be manufactured from ASTM-A240 annealed and pickled sheets and plates in accordance with ASTM A778 in Grade TP [304L or 316L] stainless steel. Pipe shall be manufactured to nominal pipe sizes as listed in ANSI B36.19, Table 2, and shall have [ the following nominal wall thickness. ]

Nominal Pipe Size
(IN.) Actual O.D.
(IN.) Schedule/Gauge/Plate Nom. Wall
Thickness (IN.)
3 3.500 Sch. 5s 0.083”
4 4.500 Sch. 5s 0.083”
6 6.625 Sch. 5s 0.109”
8 8.625 Sch. 5s 0.109”
10 10.750 12 Ga. Sheet 0.109”
12 12.750 12 Ga. Sheet 0.109”
14 14.000 11 Ga. Sheet 0.125”
16 16.000 11 Ga. Sheet 0.125”
18 18.000 11 Ga. Sheet 0.125”
20 20.000 10 Ga. Sheet 0.140”
24 24.000 3/16” Plate 0.188”
30 30.000 3/16” Plate 0.188”
36 36.000 3/16” Plate 0.188”
42 42.000 1/4” Plate 0.250”
48 48.000 1/4” Plate 0.250”
54 54.000 5/16” Plate 0.312”
60 60.000 5/16” Plate 0.312”

[ The above table lists our standard light wall piping thickness’ which are generally lighter than schedules 5s and 10s. As an alternative, the designer may specify a schedule 10S nominal wall. or a schedule 5s nominal wall. ]

B. Fittings shall be butt weld type manufactured in accordance with ASTM-A-774 of the same grade (alloy) and in the same thickness
as the pipe. Long radius elbows (i.e. centerline to end of elbow equals 1.5 times the nominal pipe size) up to 24” diameter shall be smooth flow type. All short radius, special radius, and reducing elbows; and long radius elbows greater than 24” diameter shall be of mitered construction with at least (5) miter sections for 90 degree bends, (3) mitered sections for 45 and 60 degree bends, and (2) mitered sections for 30 degree and smaller bends.
Reducers may be straight tapered, cone type. Tees, crosses, laterals and wyes may be shop fabricated from the specified pipe.

C. The finish on the raw material, manufactured to ASTM A-240 will be
No. 1, HRAP (hot rolled annealed and pickled) or better. The finish on the completed pipe and fittings shall be as specified in ASTM A778 and A774, respectively.

D. Grade TP316L products may be substituted for TP 304L products. Heavier wall pipes or fittings may be substituted for a lighter wall thickness specified. ASTM A312 pipe and A403 fittings may be substituted for A778 and A774 products, respectively.

2.02: Flanges, 3” diameter and larger

[The following is our standard economical lightweight flange specification. The designer is to determine the proper flange for their applications]

A. Flanged pipe ends shall be made up of grade TP [ 304L or 316L ] stainless steel slip-over type rolled angle face rings and hot dipped galvanized steel or ductile iron backing flanges drilled to ANSI 16.1 class 125 standard. The angle face ring thickness shall be equal to or greater than the wall of the pipe or fitting to which it is welded and it shall be continuously welded on both sides to the pipe or fitting. The angle leg shall not interfere with the flange boltholes. The back-up flanges shall be supplied with the following nominal thickness.

Nom. Pipe Size (IN.) Flange Thickness (IN.)
3 1/2
4 9/16
6 – 10 5/8
12 – 16 3/4
18 – 20 7/8
24 – 30 1
36 1-1/8
42 1-1/4
48 1-3/8
54 1-3/8
60 1-1/2

[ Backing flanges can be specified to be our standard lightweight stainless steel, if desired. Substitute ‘TP [ 304 or 316 ] stainless steel’ for ‘hot dipped galvanized steel or ductile iron’ in the above paragraph and follow with the table below. ] Nom. Pipe Size (IN.) Flange Thickness (IN.)
3 – 8 1/2
10 – 14 5/8
16 – 20 3/4
24 – 30 1
36 -54 1 1/4
60 13/8

2.03: Couplings

A. The piping will be shop prepared for pipe couplings where shown on the

1. Sleeve type couplings shall be of standard steel construction [specify gaskets, coating etc]. Pipe shall be plain end with external weld beads ground smooth to insure proper gasket seating. For pressure pipe lines, sleeve coupling joints will be restrained where indicated on the drawings. Restraint shall be by the use of harness rods connecting across the joint to plate lugs on adjacent flange joints. Where no adjacent flange joints exist, stainless steel harness lugs, as detailed on the drawings, shall be welded to the pipe to receive the harness rods. All sleeve couplings, plate lugs, harness rods and hardware will be provided by the contractor.

2. Arched band type couplings shall be stainless steel of equal or superior alloy as the pipe and will be Depend-O-Lok type as manufactured by Victaulic or equal. Couplings will be Fixed – FxF, Expansion – ExE, or Fixed by Expansion – FxE as noted on the drawings. The pipe shall be plain end with external weld beads ground smooth and with stainless steel restraining rings shop welded to the piping ends for fixed type couplings. [specify gaskets]

3. Split type couplings shall be malleable iron or ductile iron, Style 77, as manufactured by Victaulic. Gaskets shall be suitable for the service conditions. The pipe ends shall be roll grooved to the coupling manufacturers specifications. Where roll grooving is impractical, the pipe shall have heavy wall, schedule 40s minimum, machine grooved pipe nipples or machined ring collars fully welded to the pipe or fitting ends. Nipples shall be taper bored to the I.D. of the adjoining pipe to allow full weld penetration. Collars shall be welded on both sides to the piping. Nipples and collars shall be of the same alloy as the piping.

4. Expansion couplings shall be the flanged rubber arch type specified in section ( ). Pipe flanges shall be provided for these couplings where shown on the drawings.

2.04: Threaded Connections

A. Threaded pipe, gauge or instrument connections shall be made using
stainless steel 3000-pound threaded half couplings conforming to
ASTM A182 or ASTM A-276, shop welded to the pipe at the locations
shown on the drawings.

2.05: Joints

A. Flanges shall be provided as a minimum at all flanged valves, meters,
couplings, and other equipment. Couplings will be provided where shown
on the drawings.

B. Pipe and fitting spools shall be shop fabricated to the fullest extent
possible in 40’0” maximum lengths with 7’6” maximum widths for
efficient commercial transport to the project site. Spools with
fittings may exceed 40’0” so long as length allows commercial
transport. Smaller pipe spools shall be provided with joints as shown
on the drawings for special handling, installation, and/or disassembly

C. All other joints required for shipping, handling and installation of the
piping spools shall be (field welds, flange joints, sleeve couplings,
band couplings, or split couplings).

2.06: Bolting

A. The contractor shall supply and install flange bolting as follows. [specify]


A. After the manufacture of individual stainless steel fittings and pipe
lengths, they shall be pickled by immersion in a tank containing an
ambient nitric hydrofluoric acid solution made up from Oakite
Deoxidizer SS, or equal, and monitored to generally maintain a 25%
or higher solution by volume of water. The duration of immersion shall
be 15 to 20 minutes and may be supplemented by manually scrubbing
or brushing with non metallic pads or stainless steel wire brushes.
The acid treatment shall be followed by immersion in a rinse water
tank, followed if necessary by a spray rinse. The stainless steel
products shall then be allowed to air dry to achieve passivation.

B. Welding of pipe spools shall be performed using welders and
procedures qualified in accordance with ASME Section IX. Piping
with wall thicknesses up to and including 11 gauge (o.125”) shall be
welded with the TIG (GTAW) process. Heavier walls shall be beveled
according to procedure, root pass welded with the TIG (GTAW), and
have subsequent weld passes performed using the TIG (GTAW),
MIG (GMAW), or Metallic Arc (SMAW) process. Filler metal of equal
or superior ELC grades only shall be added to all welds to provide a
cross section at the weld equal to or greater than the parent metal.
Weld deposit shall be smooth and evenly distributed; weld reinforce-
ment shall be as follows.

Wall Thickness Weld Reinforcement (Max)
I.D. O.D.
Up to 12 Ga. (0.109”) 1/16” 3/32”
11 Ga. (0.125”) to 3/16” Pl. 3/32” 1/8”
1/4” Plate & Larger 1/8” 3/16”

Concavity, undercut, cracks or crevices shall not be allowed. Butt
welds shall have full penetration to the interior surface, and inert
argon gas shielding shall be provided to the interior and exterior of
the joint. Angle face rings shall be continuously welded on both sides
to pipe or fitting. Exterior welds, such as the back side of face rings or
flanges and structural attachments, may be welded by the MIG (GMAW)
or Metallic Arc (SMAW) process; however care must be taken to avoid
melting through to the interior surface on very light walls. Excessive
weld deposits, slag, spatter and projections shall be removed by grinding.
Welds on gasket surfaces shall be ground smooth.

C. Spools shall be fabricated to the “Pipe Fabrication Institute” fabricating
tolerances ES-3 (1981).

D. After shop fabrication into pipe spools, exterior welds shall be manually
scrubbed or brushed with non metallic pads or stainless steel wire
brushes to remove weld discoloration, rinsed with clean water and
allowed to air dry.

E. All fabricated piping shall have openings plugged and flanges secured
for storage and/or transport after fabrication. All fabricated piping shall
be piece marked with identifying numbers or codes which correspond
to the contractors layout and installation drawings. The marks will be
located on the spools at opposite ends and 180 degrees apart.

F. The piping supplier during manufacturing, fabrication and handling
stages, and the contractor during handling and installation stages,
shall use extreme care to avoid the contact of any ferrous materials
with the stainless steel piping. All saws, drills, files, wire brushes, etc.
shall be used for stainless steel piping only. Pipe storage and
fabrication racks shall be non ferrous or stainless steel or rubber
lined. Nylon slings or straps or alloy chains or cable shall be used
for handling stainless steel piping. After installation, the contractor
shall wash and rinse all foreign matter from the piping surface. If
rusting of embedded iron occurs, the contractor shall pickle the
affected surface with Oakite Deoxidizer SS or equal, scrub with
stainless steel brushes and rinse clean.

G. After installation, the contractor shall paint all steel or iron flanges,
couplings and appurtenances in accordance with Section ( ).
Painting of the stainless steel pipe is not required. However, the
contractor shall be responsible for supplying and installing the
stainless steel piping with a consistently clean surface. Identifying
spool piece marks shall be removed with paint thinner or solvents
and the entire stainless steel surface shall be washed with detergent
and rinsed clean. Final marking of the pipeline will be in accordance
with ( ).

H. After installation, the piping system shall be tested by the Contractor
according to ( ).