WS trench covers – GT and GU – US, AU & EU standards

Where trench covers are used

Grating trench covers close drainage trenches, cable and pipe ditches, subway and air pits on walkways, carriageways, courtyards, plants and ports. A system has a fixed frame cast into the concrete and a movable grating cover; hot-dip galvanising protects both. Hinged covers resist theft and are easy to open.

Sections through GT and GU trench covers — WS-GT angle seat frame and WS-GU banded angle systems.

WS load classes

WS trench and pit cover load classes
WS class	Fully laden vehicle (kg)	Rear single-wheel load (kN)	Wheel contact area a × b (mm)
T-25	25,000	100	200 × 500
T-20	20,000	80	200 × 500
T-14	14,000	56	200 × 500
T-6	6,000	24	200 × 240
T-2	2,000	8	200 × 160

Except for highways, GT covers suit all roads with moderate traffic; bolting covers down is recommended against displacement. Typical gratings are WS-G…/30/100; for public areas a 50 mm cross bar pitch is recommended. Serrated and I-bar gratings are available on request.

WS classes are defined by wheel load. Where AASHTO, AS 3996 or EN 124 classes are specified, the cover is designed – and where required tested – to that standard.

WS-GT covers – T-2 and pedestrian

WS-GT, class T-2
Trench width (mm)	Type	Grating b × a × h (mm)	kg	Seat angle
100	WS-GT100-20	995 × 160 × 20	4.0	L40×25×5
120	WS-GT120-20	995 × 180 × 20	4.4	L40×25×5
150	WS-GT150-20	995 × 210 × 20	5.2	L40×25×5
180	WS-GT180-20	995 × 240 × 20	5.7	L40×25×5
200	WS-GT200-20	995 × 260 × 20	6.0	L40×25×5
240	WS-GT240-25	995 × 304 × 25	13.4	L40×28×3
300	WS-GT300-25	995 × 364 × 25	15.9	L40×28×3
360	WS-GT360-25	995 × 424 × 25	18.3	L40×28×3
400	WS-GT400-25	995 × 464 × 25	19.7	L40×28×3
450	WS-GT450-32	995 × 544 × 32	28.8	L56×36×4
500	WS-GT500-45	995 × 580 × 45	42.2	L50×50×5
600	WS-GT600-50	995 × 690 × 50	54.8	L56×56×6

WS-GT, pedestrian
Trench width (mm)	Type	Grating b × a × h (mm)	kg	Seat angle
100	WS-GT100-25	995 × 164 × 25	8.2	L40×28×3
120	WS-GT120-25	995 × 184 × 25	9.2	L40×28×3
150	WS-GT150-25	995 × 214 × 25	10.2	L40×28×3
180	WS-GT180-25	995 × 244 × 25	11.3	L40×28×3
200	WS-GT200-32	995 × 294 × 32	16.6	L56×36×4
240	WS-GT240-32	995 × 334 × 32	18.7	L56×36×4
300	WS-GT300-38	995 × 416 × 38	26.7	L70×45×8
360	WS-GT360-45	995 × 440 × 45	33.0	L50×50×5
400	WS-GT400-50	995 × 490 × 50	40.0	L56×56×6
450	WS-GT450-50	995 × 540 × 50	43.4	L56×56×6
500	WS-GT500-50	995 × 590 × 50	47.4	L56×56×6
600	WS-GT600-55	995 × 700 × 55	60.8	L60×60×5

WS-GT covers – T-14, T-20 and T-25

WS-GT, class T-14
Trench width (mm)	Type	Grating b × a × h (mm)	kg	Seat angle
100	WS-GT100-25	995 × 164 × 25	8.2	L40×28×3
120	WS-GT120-25	995 × 184 × 25	9.2	L40×28×3
150	WS-GT150-25	995 × 214 × 25	10.2	L40×28×3
180	WS-GT180-32	995 × 274 × 32	15.7	L56×36×4
200	WS-GT200-32	995 × 294 × 32	16.6	L56×36×4
240	WS-GT240-38	995 × 356 × 38	23.2	L70×45×8
300	WS-GT300-45	995 × 380 × 45	28.8	L50×50×5
360	WS-GT360-50	995 × 440 × 50	36.5	L56×56×6
400	WS-GT400-50	995 × 480 × 50	39.3	L56×56×6
450	WS-GT450-55	995 × 550 × 55	48.9	L60×60×5
500	WS-GT500-60	995 × 610 × 60	58.6	L65×65×5
600	WS-GT600-75	995 × 750 × 75	87.9	L80×80×5

WS-GT, class T-20
Trench width (mm)	Type	Grating b × a × h (mm)	kg	Seat angle
100	WS-GT100-25	995 × 164 × 25	8.2	L40×28×3
120	WS-GT120-32	995 × 214 × 32	12.9	L56×36×4
150	WS-GT150-32	995 × 224 × 32	14.3	L56×36×4
180	WS-GT180-38	995 × 296 × 38	19.7	L70×45×8
200	WS-GT200-38	995 × 316 × 38	21.1	L70×45×8
240	WS-GT240-45	995 × 320 × 45	25.0	L50×50×5
300	WS-GT300-50	995 × 390 × 50	32.6	L56×56×6
360	WS-GT360-55	995 × 400 × 55	41.6	L60×60×5
400	WS-GT400-55	995 × 500 × 55	44.7	L60×60×5
450	WS-GT450-65	995 × 590 × 65	59.3	L70×70×5
500	WS-GT500-75	995 × 640 × 75	75.9	L80×80×5

WS-GT, class T-25
Trench width (mm)	Type	Grating b × a × h (mm)	kg	Seat angle
100	WS-GT100-32	995 × 194 × 32	11.4	L56×36×4
120	WS-GT120-32	995 × 214 × 32	12.9	L56×36×4
150	WS-GT150-38	995 × 266 × 38	18.1	L70×45×8
180	WS-GT180-45	995 × 260 × 45	20.9	L50×50×5
200	WS-GT200-45	995 × 280 × 45	22.2	L50×50×5
240	WS-GT240-45	995 × 320 × 45	25.0	L50×50×5
300	WS-GT300-50	995 × 390 × 50	32.6	L56×56×6
360	WS-GT360-55	995 × 460 × 55	41.6	L60×60×5
400	WS-GT400-65	995 × 520 × 65	54.7	L70×70×5
450	WS-GT450-75	995 × 590 × 75	70.3	L80×80×5

WS-GU covers

For concrete trenches without an edge frame – especially precast U-channels – the GU cover is the simplest and most economical choice: the banded angle sits directly on the trench edges. Filling the top edge with angle steel is recommended for T-6 and T-14 loads. GU covers suit side ditches where cars pass occasionally.

WS-GU, class T-2 and pedestrian
Trench width (mm)	Type	Grating b × w × h (mm)	Banded angle	kg
100	WS-GU100-20	995 × 90 × 20	L30×3	4.4
120	WS-GU120-20	995 × 110 × 20	L30×3	5.0
150	WS-GU150-20	995 × 140 × 20	L30×3	5.5
180	WS-GU180-20	995 × 170 × 20	L30×3	6.0
200	WS-GU200-25	995 × 190 × 25	L40×5	12.2
240	WS-GU240-25	995 × 230 × 25	L40×5	13.9
300	WS-GU300-25	995 × 290 × 25	L40×5	16.0
360	WS-GU360-25	995 × 350 × 25	L40×5	18.4
400	WS-GU400-32	995 × 390 × 32	L40×5	23.7
450	WS-GU450-32	995 × 443 × 32	L40×5	26.3
500	WS-GU500-45	995 × 488 × 45	L50×6	41.7
600	WS-GU600-50	995 × 588 × 50	L56×6	53.8

Installation

Brace the frames to hold the trench width, set them to finished floor level and compact concrete under the seating flange; leave covers in place during the pour. Clean the seat after curing, place covers in their marked positions and fit lock-down bolts. Repair any zinc damage with zinc-rich paint.

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Hoa Kỳ

AASHTOVehicle loading H-20 / HS-20, HL-93
ANSI/NAAMM MBG 532Heavy-Duty Metal Bar Grating Manual
ACI 318 Ch. 17Anchoring to concrete
AWS D1.1Structural welding code – steel
ASTM A123Hot-dip galvanized coatings

Road-trafficked covers: AASHTO H-20 / HS-20 or HL-93 commonly specified

Tất cả tiêu chuẩn United States →

Úc / NZ

AS 3996-2019Access covers and grates
AS 5216Fastenings in concrete
AS/NZS 1554.1Structural steel welding
AS/NZS 4680Hot-dip galvanized coatings

Load class: Class A to G by location (AS 3996-2019)

Tất cả tiêu chuẩn Australia & New Zealand →

Châu Âu

EN 124Gully tops and manhole tops for vehicular and pedestrian areas
EN 1992-4Design of fastenings for use in concrete
EN ISO 1461Hot-dip galvanized coatings

Load class: A15, B125, C250, D400, E600 or F900 (EN 124)

Tất cả tiêu chuẩn Europe →

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Hoàn thiện bề mặt	Tiêu chuẩn / ghi chú
Hot-dip galvanised (G)	ASTM A123 · AS/NZS 4680 · EN ISO 1461
Duplex	Galvanised + paint for colour or C5 environments

Hoàn thiện bề mặt

Tiêu chuẩn / ghi chú

Hot-dip galvanised (G)

ASTM A123 · AS/NZS 4680 · EN ISO 1461

Duplex

Galvanised + paint for colour or C5 environments

Câu hỏi thường gặp

What is the difference between GT and GU?

GT covers sit in a steel angle seat frame cast into the trench edges; GU covers have a banded angle that sits directly on the edges of a concrete or precast U-channel – simpler and cheaper, for lighter traffic.

Which class for a factory road?

Usually T-14 to T-25 depending on the heaviest truck; pedestrian or T-2 for walkways and car areas. The designer confirms the class.

Can covers be locked?

Yes – bolt-down covers and hinged covers are available to prevent displacement and theft.