Drainage Solutions in Steel

Armtec first introduced Hel-Cor pipeto the construction industry in 1970.Since then, Hel-Cor has proven itseffectiveness and durability in countless installations, under diverseconditions.

The inherent strength of these helically-corrugated, light-weightsteel sections, in conjunction withthe diversity of sizes, couplings, fittings, and finishes, combine tomake Hel-Cor one of the most versatile, cost-effective systems forapplications such as:

• Culverts

• Sewers

• Stream Enclosures

• Underpasses

• Intakes

• Outfalls

• Water transmission lines

The annular corrugated pipe ends,when fitted with Hugger bands and O-ring gaskets, provide conduits with very low rates of infiltration and exfiltration.

Hel-Cor is available in diametersranging from 150 to 3600 mm, intwo shapes (full-round and pipe-arch); two corrugations; five wallthicknesses; and three factory-applied finishes. The material andfabrication of Hel-Cor Lock SeamPipe conforms to CSA StandardCAN/CSA G401.

Flexibility and HighCompressive StrengthThe helical corrugations and continuous lock-seam provide high ring compression strength in a relatively light-weight,

thin-walled structure.

Vertical live and dead-loads aretransferred to the surrounding soil,thus creating a composite steel/soilinteraction, effectively distributingthe load around the entire circumfer-ence. Unit pressure on the top andbottom of the pipe can be as little asone third of that encountered withrigid pipe under identical conditions.

Economy of InstallationDepending upon the installation, costsavings in excess of 25% over othersystems are not uncommon.

The long, light-weight sections ofHel-Cor pipe lend themselves to fast,easy handling and installation withlight equipment and simple tools.

Shapes: The full-round pipe is usedfor most typical, general-purposeapplications.

Pipe-arch is used where headroom islimited. The low, wide pipe-arch shapeprovides the required hydrauliccapacity at lower depths of flow. Forfast, unrestricted run-off at low waterlevels, the pipe-arch is very effective.

Selection guides for full round andpipe-arch are shown in Tables 6 to 14.

Corrugations: Hel-Cor lock-seam pipe is supplied in three corrugations:38 x 6.5 mm, 68 x 13 mm, and 125 x26 mm. The latter provides additionalstiffness, which is especially impor-tant with larger pipes to minimizedeflection during backfilling. Refer topages 6 and 7 for the section proper-ties of the three corrugations.

Drainage Solutions in SteelHel-Cor Lock-Seam Corrugated Steel Pipe

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Rigid Ring Compression

Flexible Ring Compression

NominalPitch Depth Inside Diameter (mm)

38 6.5 150, 200, 25068 13 300 - 2000125 26 1200 - 3600

Table 1 - Corrugation Profiles (mm) & Diameters

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Durability Considerations –Three FinishesTo accommodate a variety of durability and hydraulic design considerations, three factory-appliedfinishes are available. These areGalvanized Steel, Aluminized SteelType 2 and Polymer Coated Steel.

Galvanized Steel: This standard general-purpose finish is a continuous galvanized coatingapplied using stringent quality control procedures to ensure excellent bonding of the coating tothe steel. These installations haveproven their durability in many yearsof field application.

Generally, most culvert and stormsewer sites in Canada experience relatively neutral conditions. Theheavy zinc coating of the standardgalvanized finish provides sufficientprotection in most installations.

Aluminized Steel Type 2: For morecorrosive environments, Armtec recommends the use of AluminizedSteel Type 2. The aluminum coatinghas superior corrosion resistancethan zinc galvanizing and displaysbetter abrasion resistance. Mostagencies use a service life estimatethat is significantly greater than thatof plain galvanized steel.

Polymer Coated CSP: In particularly aggressive environments consideration should be given to theuse of polymer coated corrugatedsteel pipe. Polymer coated CSP utilizes galvanized steel protected bya mechanically and chemically laminated polymer film on both

sides of the steel sheet. This product combines the strength ofsteel with the durability of high density polymer.

Annular Corrugated Ends:Couplers and FittingsHel-Cor pipe features universalannular corrugated ends, so a varietyof couplings may be used for thepipe and pipe-arch.

Three types of couplers are recommended:

• Hugger Band

• Annular corrugated standard boltand angle coupler

• Dimpled coupling band

Hugger Band: Armtec offers a highly effective Hugger Band joint.These 500 mm wide bands are recommended for storm sewers andother installations where low leakagerates and resistance to longitudinaldisjointing are prime requirements.

When used with O-ring gaskets, theHugger Band provides an extremelytight joint with low infiltration andexfiltration rates.

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Standard Annular CorrugatedCoupler: The standard annular corrugated coupler, fitted with boltand angle attachments, seats snugly onto the pipe-end corrugations, and is suitable for most general-purpose applications.

Dimpled Coupling Band: This coupler is used where helical and/orannular corrugated pipe ends are tobe coupled. Dimpled couplers areavailable with steel angles or withwedge connectors as shown.

Angle Type: 300 to 1800 mmWedge Type: 300 to 1200 mm

Typical FittingsFittingsStandard fittings such as: tees, wyes, elbows, saddle branches, and reducers are available for theround pipe and pipe-arch.

Special fittings, such as manholesand catchbasins can be custom-fabricated to suit individual requirements.

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End-TreatmentsArmtec supplies durable, lightweightend-sections for improved hydraulicefficiency and erosion control. Thesesections help reduce scour at inletsand undermining at outlets, while providing an attractive, economicalmeans of blending the culvert endswith the sloping embankment.

There are a variety of end finishesavailable for corrugated steel pipe.These options include skewed andbevelled ends, steel and polymer endsections and a variety of headwallsand cut off walls.

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Hel-Cor Pipe andPipe-Arch68 mm x 13 mmCorrugations

Coated Design Area of Moment of Section Radius of Tangent Tangent DevelopedThickness Thickness Section Inertia Modulus Gyration Length Angle Width

(mm) (mm) (mm2/mm) (mm4/mm) (mm3/mm) (mm) (mm) (fo degrees) Factor*

1.6 1.40 1.512 28.367 4.024 4.332 19.578 26.734 1.0802.0 1.82 1.966 37.108 5.111 4.345 19.304 26.867 1.0802.8 2.64 2.852 54.565 7.114 4.374 18.765 27.136 1.0803.5 3.35 3.621 70.159 8.743 4.402 18.269 27.381 1.0814.2 4.08 4.411 86.706 10.334 4.433 17.755 27.643 1.081

* Developed width factor measures the increase in profile length due to corrugating.

Table 2 – Section Properties

Pipe End Handling Weight - Galvanized (kg/m)Diameter Area Wall Thickness (mm)

(mm) (m2) 1.3 1.6 2.0 2.8 3.5 4.2

150* 0.018 5.9 7.2200* 0.031 7.7 9.5250* 0.049 9.6 12

300 0.071 14 18400 0.126 19 24500 0.196 24 30

600 0.283 28 35 49700 0.385 33 41 57800 0.503 37 47 65

900 0.636 42 53 73 901000 0.785 58 81 1001200 1.131 70 97 120

1400 1.539 113 140 1681600 2.011 130 160 1921800 2.545 179 215

2000 3.142 239

*38 x 6.4 corrugation profile

Table 3 – Handling Weight and End Area

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Table 5 – Handling Weight and End Area

Pipe End Handling Weight - Galvanized (kg/m)Diameter Area Wall Thickness (mm)

(mm) (m2) 1.6 2.0 2.8 3.5

1200 1.131 57 71 100 1241400 1.539 83 116 1441600 2.011 95 132 165

1800 2.545 106 148 1852000 3.142 118 165 2052200 3.801 129 181 225

2400 4.524 141 197 2452700 5.726 159 222 2763000 7.069 246 306

3300 8.553 270 3363600 10.179 367

Hel-Cor Pipe 125 mm x 25 mmCorrugations

Pitch = 125 mm

T

Depth = 25 mm

TL

0

Radius = 40 mm

Coated Design Area of Moment of Section Radius of Tangent Tangent DevelopedThickness Thickness Section Inertia Modulus Gyration Length Angle Width

(mm) (mm) (mm2/mm) (mm4/mm) (mm3/mm) (mm) (mm) (fo degrees) Factor*

1.6 1.40 1.549 133.300 9.730 9.277 18.568 35.564 1.1062.0 1.82 2.014 173.720 12.489 9.287 17.970 35.811 1.1072.8 2.64 2.923 253.237 17.684 9.308 16.742 36.330 1.1073.5 3.35 3.711 322.743 21.993 9.326 15.600 36.826 1.108

* Developed width factor measures the increase in profile length due to corrugating.

Table 4 – Section Properties

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Hel-Cor Pipe Height of Cover LimitsCL-625 (CAN CSA-S6-06) and AREMA Cooper E-80 Loadings

Table 6 – 68 mm x 13 mm CorrugationsMaximum Cover in Metres

Specified Thickness in MillimetresDiameter Minimum Cover

(mm) CL-625 E-80 1.60 (mm) 2.00 (mm) 2.80 (mm) 3.50 (mm) 4.20 (mm)

300 300 300 70 91400 300 300 53 68500 300 300 42 54600 300 300 35 45 66

700 300 300 30 39 57800 300 300 26 34 50900 300 300 23 30 44 56 70

1000 300 300 21 27 40 50 631200 300 300 23 33 42 521400 300 500 27 35 43

1600 300 500 22 28 351800 500 500 22 272000 500 500 22

Table 7 – 125 mm x 25 mm CorrugationsMaximum Cover in Metres

Specified Thickness in MillimetresDiameter Minimum Cover

(mm) CL-625 E-80 1.60 (mm) 2.00 (mm) 2.80 (mm) 3.50 (mm)

1200 300 500 18 23 341400 300 500 15 20 29 351600 300 500 13 18 25 31

1800 300 500 12 16 22 282000 300 500 11 14 20 252200 300 700 10 12 18 23

2400 500 700 11 17 212700 500 700 15 183000 500 1000 13 16

3300 500 1000 143600* 700 1000 12*

* Flexibility limit exceeded – for specified use only.1. Dead load is based on a unit weight of backfill of 19kN/m3.2. Where Height of Cover exceeds the Diameter, a reduction load factor of 0.86 has been used.3. Live Load includes impact. 4. Minimum cover is taken from top of pipe to profile grade or to the top of the finished granular base.5. Special care must be taken with truck loads during construction.6. Foundation investigation is recommended practice.7. The above Height of Cover tables are industry standards, Local, Provincial or Federal standards may differ.

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Table 8 – 68 mm x 13 mm CorrugationsDiameter of Span Rise B Waterway

Pipe of Equal (mm) (mm) (mm) AreaPeriphery (Square

(mm) Metres)

400 450 340 130 .11500 560 420 165 .19600 680 500 190 .27

700 800 580 220 .37800 910 660 255 .48900 1030 740 265 .61

1000 1150 820 310 .741200 1390 970 375 1.061400 1630 1120 430 1.44

1600 1880 1260 500 1.871800 2130 1400 560 2.36

For weights of pipe-arches with the 68 x 13 corrugation refer to theweight of the circular pipe with the equivalent periphery.

Hel-Cor Pipe-Arch Details

Table 9 – Height-of-Cover Limits for Corrugated Steel Pipe-Arch CL-625 Live Load

Maximum Height of Fill (m)Span x Rise Minimum for the Following

(mm) Thickness Corner BearingRequired (mm) Pressures

200 kPa 300 kPa 400kPa

450 340 1.6 6.0 8.9 11.9560 420 1.6 5.9 8.9 11.8680 500 1.6 5.9 8.8 11.7

800 580 1.6 5.8 8.7 11.7910 660 1.6 5.8 8.7 11.6

1030 740 1.6 5.7 8.6 11.5

1150 820 2.0 5.7 8.5 11.31390 970 2.8 5.6 8.4 11.21630 1120 3.5 5.5 8.2 11.0

1880 1260 3.5 5.4 8.1 10.82130 1400 3.5 5.3 8.0 10.6

Min. cover from top of pipe-arch to subgrade = 300 mmCorner bearing pressures govern, in all cases.

125 mm x 25 mm Corrugations (where available)Diameter of Span Rise B Waterway

Pipe of Equal (mm) (mm) (mm) AreaPeriphery (Square

(mm) Metres)

1600 1780 1360 635 1.931800 2010 1530 650 2.442000 2230 1700 660 2.97

2200 2500 1830 750 3.442400 2800 1950 805 4.272700 3300 2080 905 5.39

3000 3650 2280 1005 6.603300 3890 2690 1090 8.293600 4370 2890 1195 9.76

Note: The pipe-arch is available with the 125 x 25 corrugation.

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First introduced by Armtec in 1925,perforated corrugated steel pipe provides a lasting system to drainground water under paved surfacessuch as roadways, parking lots, airport runways, recreational areas aswell as areas adjacent to buildings,bridge abutments and retainingwalls. It offers exceptional perform-ance for ground water drainage inlow lying areas like parklands, farmsand agricultural areas.

Perforated Hel-Cor is widely acceptedas a practical, durable, economicalmeans of controlling unwantedground water. This solution is effi-cient and costs less than repeatedsurface repairs and virtually elimi-nates maintenance concerns.

Perforated pipe is available in plaingalvanized for most applications. Inparticularly aggressive environments,it is strongly recommended that con-sideration be given to using eitherAluminized Steel Type II.

Pipe Size SelectionFor normal subdrainage, the infiltration of ground water is veryslow. Therefore, approximately 150metres of 150 mm diameter pipemay be used as an interceptor before

any increase in pipe diameter isrequired. Where extremely perviousmaterial is being drained or wheresprings are encountered, larger sizesmay be required.

Placing of PerforationsArmtec recommends that the pipe beplaced with the perforations down.This hinders solids from entering thepipe and keeps the water table lower.

Recommended BackfillThe trench should be excavated withapproximately 100 mm of clearanceat the sides of the pipe so that pervious backfill can surround thepipe. For the filter backfill, concretesand or other commonly availablecoarse sand-gravel mixtures performsatisfactorily for perforated pipe inmost soils.

GeotextileGeotextile is widely used in perforated pipe applications, particularly where graded filtermaterial is not available. Armtec canprovide a low-cost knitted polyestersock to encase the pipe. More criticalinstallations call for a high qualitynon-woven geotextile such asArmtec 140 to separate the trenchfillfrom the native material.

Pipe OutletsPerforated pipe’s cantilever strengthmakes it ideal for use as a projectingpipe outlet.

Free outlets are important, and thefailure of subdrains to properly function can often be attributed toplugged, damaged or improper outlets. Outlet pipes should be protected from damage by maintenance equipment. A suitablebarrier such as a hinged rodent trapshould be used to keep out wildlifewhose nests could cause clogging.

Spacing of LateralsDraining large, comparatively flatareas usually requires a parallel orherringbone system of drainage pipe.table No. 10 may be used as a gener-al guide in laying out the system. Thespacing used on highways and rail-ways is controlled by the location ofthe water-bearing strata.

Perforated Hel-Cor® PipeFor Ground Water Control

Standard Perforations

Nominal Minimal No. Minimum Width NormalInternal of Rows of Unperforated Thickness

Diameter Perforations Segment Specified

150 mm 6 110 mm 1.3 mm

200 mm 6 150 mm 1.3 mm

250 mm 6 185 mm 1.6 mm

300 mm 6 230 mm 1.6 mm

400 mm 6 305 mm 1.6 mm

* Random hole spacing around the circumference is available on request.

Table 10 - Dimensions, Thicknesses and Spacing of Perforations*

*All perforations nominal 10 mm diameter

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Hel-Cor Installation: Bedding and BackfillingWell graded, drainable backfill is recommended for good compaction.The designer should refer to the gradation and backfill specificationsof the appropriate provincial highwaystandard. Stumps, rocks, frozen lumpsand other debris should be removedfrom the bedding site.

Round pipe can be built on a flatsand cushion with rodding and tamp-ing of the backfill around thehaunches. Alternatively, the pipe can be installed on a pre-shapedgranular base.

The pipe-arch bottom arc must be erected on a pre-shaped sandcushion. The support under the bottom arc should be relatively yielding but under the cornerhaunches the supporting groundmust be highly stable. Special attention should be given to compacting the backfill around thecorner arcs where the highest soilpressures develop.

Backfill should be spread in 150 mmlayers alternating from one side ofthe pipe to the other, and shouldextend above the pipe to a minimumheight of 300 mm or one sixth thespan, whichever is greater.

Compaction using suitable mechanical equipment should be carried out to achieve the specifiedbackfill density.

Care must be taken to ensure that thepipe or pipe-arch is not damaged byheavy equipment traffic during con-struction.

Head Office: 370 Speedvale Ave. W., P.O. Box 3000, Guelph, ON N1H 6P2wwwwww..aarrmmtteecc..ccoommSales Offices: Nanaimo, Prince George, Langley, Edmonton, Calgary, Lethbridge,Saskatoon, Winnipeg, Thunder Bay, Sudbury, Guelph, Peterborough, Chesterville,Forest, Orangeville, Comber, Montreal, Quebec City, St. Clet, Sackville, Truro,Sleeman Park, Bishop’s Falls and St. John’s.

DS/30C/BP/1108

Other uses for Hel-Cor Corrugated Steel Pipe

• Void Tubes

• Hickenbottom Drains

• Firewater Tanks

• Utilidors

Wind Farms Pole Cribs

Stormwater Detention Tanks Temporary Smoke Stacks Relines