DIN SPEC 1808813:2019 Structures For Wind Turbines And Platforms Part 13: Execution Of Offshore Steel Structures; Text In German And English

Datum:2019 Dezember

DIN SPEC 18088-13

Structures for wind turbines and platforms — Part 13: Execution of Offshore Steel
structures; Text in German and English

Tragstrukturen fiir Windenergieanlagen und Plattformen — Teil 13: Ausfiihrung von Offshore-Stahlbauten; Text
Deutsch und Englisch
Structures

des éoliennes

Stand 2019-12

allemand et anglais

et des

plateformes
—

Partie 13:

Exécution

des

structures

offshore

en acier; Texte

en


DIN SPEC 18088-13:2019-12

Contents
Page
Foreword...

4

Introduction.

5

1

Scope...

2

Normative references...

-6

3

Terms and definitions...

9

4
4.1

Specifications and documentation...
Execution specification.

9
9

5
52
5.3
5.4
5.4.1

Constituent products
Identification, inspection documents and traceability..
Structural steel products
Steel castings...
Mechanical properties..

9
9
10
11
11

Structural bolting assemblies for preloading
Grouting materials

15
15

4.1.2

5.4.2
5.6

5.6.4
5.9

6
6.2
6.4
6.4.1
6.5

6.5.3
6.5.4
6.6

6.61

6.6.3.

7

7.1
7.5.5

7.5.18
7.6
7.6.2

8

Non-destructive testing.
Mechanical fasteners.

Preparation and assembly
Identification.
Cutting.
General
Shaping
Flame straightenin;
Cold forming..
Holing..

Dimensions of hole:

Execution of holing.

Welding
General
Preheating.

Shear Keys..

Acceptance criteria
Fatigue requirement:
Mechanical fastening.....

8.5
8.5.1

Tightening of preloaded bolting assemblies..
General...

10

Surface treatment...

11
11.2

Geometrical tolerances
Essential tolerances...

12

Inspection, testing and correction...

8.5.7.
1

Execution classes...

10.2

11.2.2

Tolerances and gaps at fatigue-loaded joints.

Preparation of steel surfaces for paints and related products......

Manufacturing tolerance:

6

9

13
15

15
15
15
15
15

15
16
16

16
16

DIN SPEC 18088-13:2019-12

12.4

Welding

12.4.1 General
12.4.2 Inspection after weldin;
12.5 Mechanical fastening..
12.5.2 Inspection and testing of preloaded bolted connection:
Annex B (normative) Geometrical Tolerances.
B.2
Manufacturing tolerances

E1

E2
E3
E4

General....

Welded joints in hollow sections.

Rules for start and stop pos:
Preparation of joint faces
Assembly of the tubular node

Annex F (normative) Corrosion protection
Surfaces in preloaded connections..

1

®

Annex E (informative)


DIN SPEC 18088-13:2019-12

Foreword
This document has been prepared by Working Committee NA 005-08-14 AA “Fabrication of steel structures
(national mirror committee for CEN/TC 135 and ISO/TC 167)” of DIN-Normenausschuss Bauwesen (DIN
Standards Committee Building and Civil Engineering).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. DIN shall not be held responsible for identifying any or all such patent rights.
DIN SPEC are not part of the German body of standards.
A DIN SPEC developed in accordance with the prestandard procedure is the result of standards work which
DIN does not publish as a standard because there are certain reservations regarding content, or because it
was not prepared in accordance with the normal procedures for standards work.
No draft has been published for the present DIN SPEC.

Stand 2019-12

We welcome feedback on this DIN SPEC
—

preferably in the form of a file with a table, e-mailed to The template for this table is
available for download from />
—

or send a hard copy to DIN-Normenausschuss Bauwesen (DIN Standards Committee Building and Civil
Engineering), Deutsches Institut fiir Normung e. V., 10772
13267 Berlin / Germany).

Berlin (Address: Saatwinkler Damm

42/43,


DIN SPEC 18088-13:2019-12

Introduction
The document is an application-specific supplement to DIN EN 1090-2:2018-09 on steel structures for
offshore wind installations. It reflects the special design and production characteristics of these products. All
other provisions of EN 1090-2 remain fully valid where not otherwise excluded or limited here.

Stand 2019-12

The structure of DIN EN 1090-2:2018-09 was used for this Specification to make it easier to use the two
documents together. The numbering of DIN EN 1090-2:2018-09 has been continued in the numbering of text
of the present document.


DIN SPEC 18088-13:2019-12

1

Scope

The document defines requirements
including foundation elements.

for the execution of steel structures for offshore wind

installations

The document supplements the provisions of DIN EN 1090-2:2018-09.

2

Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.

DIN 18088-3:2019-01, Structures for wind turbines and platforms — Part 3: Steel structures
DIN EN 1011-2:2001-05, Welding — Recommendation for welding of metallic materials — Part 2: Arc welding

of ferritic steels; German version EN 1011-2:2001

DIN EN 1090-2:2018-09, Execution of steel structures and aluminium
requirements for steel structures; German version EN 1090-2:2018

structures— Part 2:

Technical

DIN EN 1369, Founding — Magnetic particle testing

DIN EN 1370, Founding — Examination of surface condition

DIN EN 1559-1, Founding — Technical conditions of delivery — Part 1: General
DIN EN 1559-2,
castings

Founding—

Technical

conditions

of delivery— Part 2: Additional

requirements for steel

DIN EN 1993-1-1, Eurocode 3: Design of steel structures — Part 1-1: General rules and rules for buildings
DIN EN 1993-1-8:2010-12, Eurocode 3: Design of steel structures — Part 1-8: Design of joints; German version

EN 1993-1-8:2005 + AC:2009

DIN EN 1993-1-8/NA, National Annex—
structures — Part 1-8: Design of joints

DIN EN 1993-1-10:2010-12,

Nationally determined parameters— Eurocode

Eurocode 3: Design

of steel structures —

3: Design

Part 1-10: Material

through-thickness properties; German version EN 1993-1-10:2005 + AC:2009

of steel

toughness

and

DIN EN 10025-1, Hot rolled products of structural steels — Part 1: General technical delivery conditions
DIN EN 10025-3,

Hot

rolled

products

of structural

steels—

Part 3:

Technical

delivery

conditions

for

DIN EN 10025-4, Hot rolled products of structural steels—
thermomechanical rolled weldable fine grain structural steels

Part 4:

Technical

delivery

conditions

for

normalized/normalized rolled weldable fine grain structural steels

Stand 2019-12

DIN EN 10029, Hot-rolled steel plates 3 mm thick or above — Tolerances on dimensions and shape
DIN EN 10051, Continuously hot-rolled strip and plate/sheet cut from wide strip of non-alloy and alloy steels —
Tolerances on dimensions and shape
DIN EN 10067, Hot rolled bulb flats — Dimensions and tolerances on shape, dimensions and mass
DIN EN 10130, Cold rolled low carbon steel flat products for cold forming — Technical delivery conditions

DIN SPEC 18088-13:2019-12

DIN EN 10131, Cold rolled uncoated and zinc or zinc-nickel electrolytically coated low carbon and high yield

strength steel flat products
for cold forming — Tolerances on dimensions and shape

DIN EN 10160, Ultrasonic testing of steel flat product of thickness equal to or greater than 6 mm (reflection
method)

DIN EN 10163-2, Delivery requirements for surface
sections — Part 2: Plate and wide flats
DIN EN 10164, Steel products with improved
product — Technical delivery conditions

conditions

deformation

of hot-rolled

steel plates,

properties perpendicular

wide flats and

to the surface

of the

DIN EN 10204, Metallic products — Types of inspection documents
DIN EN 10210-2, Hot finished

steel structural hollow sections — Part 2: Tolerances,

DIN EN 10219-1, Cold formed
Technical delivery conditions

welded structural hollow sections of non-alloy and fine grain steels — Part 1:

properties

dimensions and sectional

DIN EN 10219-2, Cold formed welded steel structural hollow sections — Part 2: Tolerances, dimensions and
sectional properties
for fixed offshore structures — Technical delivery conditions
DIN EN 10225, Weldable structural steels
DIN EN 10306, Iron and steel — Ultrasonic testing ofH beams with parallel flanges and IPE beams
DIN EN 10340, Steel castings for structural uses

DIN EN 12668-1,

Non-destructive

testing—

Characterization

and

verification

of ultrasonic examination

DIN EN 12668-2, Non-destructive
equipment— Part 2: Probes

testing—

Characterization

and

verification

of ultrasonic

examination

DIN EN 12668-3, Non-destructive testing—
equipment - Part 3: Combined equipment

Characterization

and

verification

of ultrasonic

examination

equipment— Part 1: Instruments

DIN EN 12681-1, Founding — Radiographic testing — Part 1: Film techniques
DIN EN 14399-4, High-strength structural bolting assemblies
for preloading — Part 4: System HV — Hexagon

bolt and nut assemblies
DIN EN 14399-6,
washers

High-strength

structural

bolting

assemblies for

preloading— Part 6:

Plain

chamfered

DIN EN 14399-8, High-strength structural bolting assemblies for preloading — Part 8: System HV - Hexagon fit

bolt and nut assemblies

Stand 2019-12

DIN EN ISO 2063, Thermal spraying — Zinc, aluminium and their alloys
DIN EN ISO 5579, Non-destructive testing — Radiographic testing of metallic materials using film and X- or
gamma rays — Basic rules

DIN EN ISO 5817:2014-06,

Welding— Fusion-welded joints in steel, nickel, titanium and their alloys (beam

welding excluded) — Quality levels for imperfections (ISO 5817:2014); German version EN ISO 5817:2014


DIN SPEC 18088-13:2019-12

DIN EN ISO 6520-1,

Welding and allied processes—

materials — Part 1: Fusion welding

Classification of geometric imperfections in metallic

DIN EN ISO 8501-3, Preparation of steel substrates before application of paints and related products — —
Visual assessment of surface cleanliness — Part 3: Preparation grades of welds, edges and other areas with

surface imperfections

DIN EN ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
DIN EN ISO 9934-1, Non-destructive testing — Magnetic particle testing — Part 1: General principles
DIN EN ISO 10863, Non-destructive testing of welds—
technique (TOFD)

Ultrasonic testing —

Use of time-of-flight diffraction

DIN EN ISO 10893-2, Non-destructive testing of steel tubes— Part 2: Automated eddy current
seamless and welded (except submerged arc-welded) steel tubes for the detection of imperfections

testing

of

DIN EN ISO 10893-3, Non-destructive testing of steel tubes — Part 3: Automated full peripheral flux leakage
testing of seamless and welded (except submerged arc-welded) ferromagnetic steel tubes for the detection of
longitudinal and/or transverse imperfections
DIN EN ISO 10893-8, Non-destructive testing of steel tubes —Part 8: Automated ultrasonic testing of seamless
and welded steel tubes for the detection of laminar imperfections

DIN EN ISO 10893-10, Non-destructive testing of steel tubes — Part 10: Automated full peripheral ultrasonic
testing of seamless and welded (except submerged arc-welded) steel tubes for the detection of longitudinal

and/or transverse imperfections

DIN EN ISO 10893-11, Non-destructive testing of steel tubes— Part 11: Automated ultrasonic testing of the

weld seam of welded steel tubes for the detection of longitudinal and/or transverse imperfections

DIN EN ISO 11666, Non-destructive testing of welds — Ultrasonic testing — Acceptance levels
DIN EN ISO 13588, Non-destructive testing of welds—
technology
DIN EN ISO 13920, Welding—
angles; shape and position

General

Ultrasonic testing —

Use of automated phased array

tolerances for welded constructions— Dimensions for lengths

and

DIN EN ISO 15613, Specification and qualification of welding procedures for metallic materials — Qualification
based on pre-production welding test
DIN EN ISO 15614-1, Specification and qualification of welding procedures for metallic materials— Welding
procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys
DIN EN ISO 15626,
Acceptance levels

Non-destructive

testing

of

welds—

Time-of-flight

diffraction

technique

(TOFD)—

Stand 2019-12

DIN EN ISO 16810, Non-destructive testing — Ultrasonic testing — General principles
DIN EN ISO 17640:2018-03, Non-destructive testing of welds — Ultrasonic testing — Techniques, testing levels,
and assessment (ISO 17640:2017); German version EN ISO 17640:2017
DIN EN ISO 19232-3, Non-destructive testing — Image quality of radiographs — Part 3: Image quality classes

ASTM E

446, Standard Reference Radiographs
for Steel Castings Up to 2 in. (50,8 mm) in Thickness


DIN SPEC 18088-13:2019-12

DASt 021:2013-09, DASt Guideline — Hot-galvanized bolting assemblies M39 to M72 as in DIN EN 14399-4,
DIN EN 14399-6

3

Terms and definitions

For the purposes
apply.

of this document,

the terms and definitions given in DIN EN 1090-2, and the following

DIN and DKE maintain terminological databases for use in standardization at the following addresses:
—_

DIN-TERMinologieportal: available at />
—

DKE-IEV: available at />
3.16
shear key
structural element on top of steel surfaces which is used to transfer shear stresses

Note 1toentry:

Shear keys are used in grouted connections to transfer loads into the concrete.

3.17

structural tube

cold-formed circular hollow
according to this standard

Note 1toentry:
conical.
4
4.1
4.1.2

section made

of structural steel which

can be fabricated

as a welded

part

Structural tubes may have circumferential and longitudinal welds. The shape can be cylindrical or

Specifications and documentation
Execution specification
Execution classes

The following rules apply in addition to DIN EN 1090-2:2018-09, 4.1.2.
Execution classes shall be specified
DIN EN 1993-1-1 and DIN 18088-3.

and

documented

when

carrying

out

analyses

according

to

Welds which join constituent products or components of different execution classes shall be assigned to the
highest execution class. If the weld can be assigned to the lower execution class, then this shall be specified
and documented by the structural designer.

5

Constituent products

5.2 Identification, inspection documents and traceability
The following rules apply in addition to DIN EN 1090-2:2018-09, 5.2.

q

In the case of structural steels for which a 3.1 inspection document is mandatory, the chemical composition
shall contain the information on 15 elements (C, Mn, Si, S, P, Al, N, Cu, Cr, Nb, V, Ti, Mo, Ni, B).

DIN SPEC 18088-13:2019-12

5.3 Structural steel products
5.3.1

General

The following rules apply in addition to DIN EN 1090-2:2018-09, 5.3.1.
The following lines are to be added to DIN EN 1090-2:2018-09, Table2

Table 2 — Product standards for structural carbon steels
Products

Technical delivery
requirements

Dimensions

Tolerances

Hot rolled bulb flats ?

DIN EN 10025

DIN EN 10067

DIN EN 10067

Plates, flats, wide flats

DIN EN 10225

Not applicable

DIN EN 10029
DIN EN 10051

Flat products, t< 3 mm

DIN EN 10130

DIN EN 10130

DIN EN 10131

Hot finished hollow
sections

DIN EN 10225

DIN EN 10210-2

DIN EN 10210-2

Cold formed hollow
sections

DIN EN 10225

DIN EN 10219-2

DIN EN 10219-2

@

Equivalence shall be demonstrated where products have been manufactured according to other technical delivery conditions.

The following properties shall be documented within the component specification:

—

Steel grade (yield strength);

—_

Steel group (impact energy/ sample position/ test temperature)

NOTE

Rules

for

selection

materials

in

the

case

of

cold

forming

are

specified

Stand 2019-12

supplemented in DIN 18088-3:2019-01, 6.3 Fracture toughness and strain ageing.

in

DIN EN 1993-1-10

and

are

—_

Delivery condition (AR, N, M, Q);

—

“Z” quality class as specified in DIN EN 10164;

—_

Strain age testing in accordance to DIN EN 10225 and compliance with the additional requirements in
DIN 18088-3;

—

Test classes for imperfections of hollow sections in accordance with DIN EN ISO 10893-8;

—

Test classes for imperfections of welded hollow sections in accordance with
DIN EN ISO 10893-3 or DIN EN ISO 10893-11;

—

Test classes for imperfections of seamless hollow sections in accordance with DIN EN ISO 10893-10;

—

Test classes for imperfections of flat products in accordance with DIN EN 10160. DIN EN 10306 shall be
applied for rolled sections by analogy.

DIN EN ISO 10893-2

or

If cold forming is to be carried out, this shall be taken into account by the designer when defining the steel

groups.

10


DIN SPEC 18088-13:2019-12

5.3.2

Thickness tolerances

In deviation from DIN EN 1090-2:2018-09, 5.3.2, the thickness tolerances for flat products made of class B
structural steels specified in DIN EN 10029 shall be complied with.

5.3.3.

Surface conditions

The following rule applies in addition to DIN EN 1090-2:2018-09, 5.3.3 item a)
The surface condition requirements also apply to the ordering and delivery of constituent products, as well
as to the finished component after processing, see also specification in 10.2 regarding surface preparation
for corrosion protection.
For unalloyed steels, class
DIN EN 10163-2.

B2

applies

to plate and

wide

flats in accordance

with

the

requirements

of

5.4 Steel castings
The following subclause applies in addition to DIN EN 1090-2:2018-09, 5.4.
5.41

Mechanical properties

The steel grades specified in Tables I and II are based on standardized cast steels (e.g. according to
DIN EN 10340). To take account of the intended use of the steels, the maximum allowable phosphorus and
sulfur contents have been reduced as compared to the original steel grades, and the impact energy value has
been specified for a temperature of —40 °C.

Stand 2019-12

Where not otherwise specified, the values in Table I and Table II apply to specimens cast according to the
reference wall thickness that qualifies the relevant lot.

11


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DIN SPEC 18088-13:2019-12

5.4.2

Non-destructive testing

5.4.2.1

General

The cast parts shall be tested using non-destructive methods under the conditions specified in the following

subclauses.

5.4.2.2

Surface testing

The required surface grade shall be defined during design analysis and is to be documented in the
component specification. Where otherwise specified, the following quality requirements apply by default.

Test method:

DIN EN ISO 9934-1 (magnetic particle testing)

Test conditions:

DIN EN 1369

Manufacturing condition:

In accordance with the purchase order (e.g. raw, processed, finished)

Surface condition:

Sand blasted (where necessary, machined)

Lot size:

100 % (all pieces)

Test scope:

Complete piece

Acceptance criteria (quality
grades):

5.4.2.3

| DIN EN 1369 — SM3 - LM2 - AM2

Internal testing

The required surface grade shall be defined during design analysis and is to be documented in the
component specification. Where otherwise specified, the following quality requirements apply by default.

Test method:

DIN EN ISO 5579 (X-ray testing RT)

Test conditions:

DIN EN 12681-1

Manufacturing condition:

In accordance with the purchase order (e.g. raw, processed, finished)

Surface condition:

Sand blasted (where necessary, machined)

Test scope:

Initial sample

Stand 2019-12

The scope may be reduced to technologically and functionally sensitive
areas if so agreed with the component specification. The areas to be
tested shall be documented by the manufacturer in drawings before
start of production.
Testing class:

DIN EN ISO 5579 —A

The image quality value:

DIN EN ISO 19232-3

Acceptance criteria (quality

Failure code

Quality class

13


DIN SPEC 18088-13:2019-12

class):

(as in ASTM E 446)

Test method:

A

Gas porosity

3

B

Inclusion of sand and slag

3

Ca

Linear shrinkage

2

Cb

Feathery shrinkage

2

Cc

Sponge shrinkage

2

Cd

Combination shrinkage

2

D

Crack

Not accepted

E

Hot tear

Not accepted

F

Insert

Not accepted

DIN EN ISO 16810 (Ultrasonic Testing)
DIN EN 12668 (all parts)

Test conditions:

DIN EN 12680-1

Manufacturing condition:

In accordance with the purchase order (e.g. raw, processed, finished)

Surface conditions:

Sand blasted (where necessary, machined)

Test scope:

Initial sample, complete piece
Ina series every piece, but the report of the component specification may
be reduced to technologically and functionally sensitive areas. The areas
to be tested shall be documented by the manufacturer in drawings before
start of production.

Acceptance criteria (quality
class):

5.4.2.4

Welding ends quality class 1 with a length
welding end), otherwise quality class 3.

(d=thickness

of

Personnel for non-destructive testing

Non-destructive testing shall be evaluated by personnel who
accordance to DIN EN ISO 9712 for the applied test method.
5.4.2.5

of 3xd

possess

at least a level 2 qualification

in

Reworking of imperfections

Stand 2019-12

Rejected surface defects like holes, pores, scabbing and sand allocations may be removed by grinding, as long
as the thickness does not drop below the nominal value, or by means of production welding.
Welding processes for reworking purposes shall be qualified in accordance to DIN EN ISO 15614-1.

5.4.2.6

Surface conditions

Surface conditions shall be assessed in accordance with DIN EN 1370.

14


DIN SPEC 18088-13:2019-12

5.4.2.7

Wall thickness

In addition to DIN EN 1559-2:
suitable test equipment.

The manufacturer shall determine

the wall thickness

of cast pieces using

5.6 Mechanical fasteners
5.6.4

Structural bolting assemblies for preloading

The following rule applies in addition to DIN EN 1090-2:2018-09, 5.6.4
The German code of practice DASt 021 may also be applied for System HV high-strength structural bolting
assemblies (DIN EN 14399-4, DIN EN 14399-6 and DIN EN 14399-8).

5.9 Grouting materials
The following rule replaces that in DIN EN 1090-2:2018-09, 5.9.

The component specification applies as regards the preparation and use of cement-based grouting materials
and mortars for load-bearing components.

6

Preparation and assembly

6.2 Identification
The following rules replace those in DIN EN 1090-2:2018-09,
fourth paragraph.

6.2, third paragraph, items a) to c) and in the

Hard stamping is not allowed on predominantly non-resting stressed components. The affected areas are
specified in the component specification. Soft stamping is allowed in these areas.
Stamping is considered as soft stamping if the stampings have a planned round notch base and an embossing
depth limited to 0,5 mm. Hard marking methods include hard stamping and milling and plasma marking.

Needle marking is classified as a soft marking method.
6.4 Cutting
64.1

General

The following rule replaces the last sentence in DIN EN 1090-2:2018-09, 6.4.1.
Remaining edges shall be broken.

6.5 Shaping
6.5.3

Flame straightening

Stand 2019-12

The following rule applies in addition to DIN EN 1090-2:2018-09, 6.5.3.
For unalloyed structural

steels

(according to DIN EN 1090-2

during flame straightening shall not exceed 580°C,

properties of structural steel.

and

this document),

the steel temperature

in order to avoid any changes

to the mechanical

If higher temperatures are to be used, proof that the properties will not be effected shall be provided in the
form of a procedure qualification test (for example as in DIN EN 1090-2).

15

DIN SPEC 18088-13:2019-12

6.5.4

Cold forming

The following rule supplements the first paragraph in DIN EN 1090-2:2018-09, 6.5.4.
Shaping by cold forming can also be done by means of roll bending.
For the selection

of material

according

to DIN 18088-3:2019-01,

6.3.1, when

DIN EN 1993-1-10:2010-12,

formula (2.4) is used, the DCF (Degree of Cold-forming) can be determined according to the following
formula:

DCF =

t

t

2n+t

2m

where
?¡ _ is the inner bending radius;
t

is the plate thickness;

r, _ is the radius at neutral fiber.
6.6 Holing
6.6.1

Dimensions of holes

The following rule supplements DIN EN 1090-2:2018-09, 6.6.1:
The hole clearance for size M39 to M72 bolts shall correspond to the specifications in DASt 021.

6.6.3

Execution of holing

The following rule differs from DIN EN 1090-2:2018-09, 6.6.3:
Holes for fasteners of class EXC3 may be made by drilling, laser, plasma
Punching is inadmissible. Burrs on holes are to be removed.

7

or other thermal

processes.

Welding

7.1 General
The following rules supplement DIN EN 1090-2:2018-09, 7.1:

Conditions for welding in cold-formed areas
DIN EN 1993-1-8:2010-12, Table 4.2 does not apply for circular hollow sections according to DIN EN 10219
and DIN EN 10225 with r;/t = 6,2 (< 7,5 %) and for cylindrical and conical shells manufactured according to
DIN EN 1090-2

with

r,/t>6,2

(<7,5%)

if a successful

strain

aging

test has

been

demonstrated.

The

Stand 2019-12

requirements for the strain aging test are specified in the component specification.

For cold-formed rectangular and square hollow sections according to DIN EN 10219 and DIN EN 10225, the
welding conditions according to DIN EN 1993-1-8:2010-12, Table 4.2 shall be observed.
7.5.5

Preheating

The following rule applies in addition to DIN EN 1090-2:2018-09, 7.5.5 first sentence.
Preheating temperatures should be determined according to DIN EN 1011-2:2001-05, Annex C, Method B.

16


DIN SPEC 18088-13:2019-12

7.5.18

Shear Keys

The following rules apply in addition to DIN EN 1090-2:2018-09.
Shear keys, if they are to be welded onto the plate surface, are specified by a minimum width on the base
material and a minimum height. The profile of the seam cross-section results from the welding process and
is not specified in more detail.
Seam

transitions,

seam

starts

and

seam

ends

are

not

to

be

ground,

unless

otherwise

specified

in

the

component specification.
For the production of shear keys, a work sample shall be produced
Minimum requirements are:

in accordance

to DIN EN ISO 15613.

—

Hardness in weld metal and heat affected zone < 350 HV 10

—

Quality level B according to DIN EN ISO 5817 for the first layer, where applicable, especially with regard
to penetration notches, but with the exception of feature 505, rough seam transition. For all other layers
quality level C according to DIN EN ISO 5817. Seam overflow / overflow is permissible as long as safety
against binding defects is guaranteed and as long as no new seam transition to the base material occurs.

An impact test is not required for qualification of welding processes for the production of shear keys.

7.6 Acceptance criteria
7.6.2

Fatigue requirements

The following rule replaces the first sentence in DIN EN 1090-2:2018-09, 7.6.2.

It is not necessary to specify the detail category or FAT class in the execution specification. The execution
requirements, including the quality level in accordance with DIN EN ISO 5817, as well as extended
requirements for the quality level, are to be specified for the individual component in the component
specification.
The following rules supplement DIN EN 1090-2:2018-09, 7.6.2:
For the application

AnnexC

of DIN EN ISO 5817,

is not applicable.

the specifications

treatments

in Table

like e.g. grinding

III apply.

DIN EN ISO 5817:2014-06,

shall be given

in the component

Stand 2019-12

specification.

Post weld

17


DIN SPEC 18088-13:2019-12

Table III — Testing according to DIN EN ISO 5817
Reference no. as in

Imperfection

DIN EN ISO 6520-1

5071

Requirement for quality level B

designation

Linear
misalignment | h < 0,1 t, but max.
between plates
specification,

6mm

or according to component

at the root side of one-sided welds max. 2 mm or % of
the seam width if this can be guaranteed for the entire
seam length.
5072

Linear
misalignment | h < 0,1 t, but max. 6mm or according to component
between tubes
specification, at the root side of one-sided welds

max.2mm

or % of the seam

width

guaranteed for the entire seam length.

505

Incorrect weld toe

if this can be

Feature to be used.

The one-sided linear misalignment (planned or unplanned), which is to be unilaterally compensated by the
seam itself in a butt weld, shall not exceed 1/4 of the seam width. Planned linear misalignment due to

changes in wall thickness at butt joints require chamfering of the thicker sheet to the thinner sheet with a
1:4 pitch if the seam width cannot compensate for the total scheduled and worst-case misalignment with a
1:4 pitch.

8

Mechanical fastening

8.5 Tightening of preloaded bolting assemblies
8.5.1

General

The following rules supplement DIN EN 1090-2:2018-09, 8.5.1:
For HV system bolting assemblies of sizes M39 to M72
preloading force Tục” and the modified torque method

with tightening method k-class K1, the nominal
apply in accordance to DIN EN 1993-1-8/NA by

analogy .
The

tightening

torques

M,

needed

for

other

to

achieve

the

nominal

preloading

force

Tục”

by

means

are

given

in

DASt 021:2013-09,
Table 6.
The process parameters
qualification tests.

tightening

methods

shall

be

determined

of procedure

The following rule replaces the penultimate paragraph in DIN EN 1090-2:2018-09, 8.5.1.
No bolting assembly shall be used if the lubrication conditions do not comply with those in the as-delivered
condition.

Stand 2019-12

8.5.7

Tolerances and gaps at fatigue-loaded joints

The following rule supplements DIN EN 1090-2:2018-09, 8.5:
A tolerance management plan shall be part of the component specification. It is mandatory for specifying
manufacturing and assembly tolerances comply with the assumed on-site boundary conditions.

18


DIN SPEC 18088-13:2019-12

10 Surface treatment
10.2

Preparation of steel surfaces for paints and related products

The following rules supplement DIN EN 1090-2:2018-09, 10.2:
For expected lives of corrosion protection greater than 15 years and corrosivity categories greater than C3,
the preparation grades shall be as specified for P2 or P3, see Table IV.
Table IV — Preparation grades for offshore structures
Description

Preparation grade according to DIN EN ISO 8501-3

1. Welds
1.1 Welding spatter

P3

Surface shall be free of all welding spatter

1.2 Rippled/ profiled weld

P2

Surface shall be dressed (e.g. by grinding) to remove irregular
and sharp-edged profiles

1.3 Welding slag

P3

Surface shall be free from welding slag

1.4 Undercut

P2

Surface as obtained

1.5 Weld porosity

P3

Surface shall be free from visible pores

1.6 End craters

P3

Surface shall be free from visible end craters

P3

Egdes shall be rounded with a radius of not less than 2 mm.

2.2 Edges made by punching, | P3
shearing, sawing or drilling

Egdes shall be rounded with a radius of not less than 2 mm

2.3 Thermally cut edges

P3

Cut surfaces are to be refinished and edges

3.1 Pits and craters

P2

Pits and craters shall be sufficiently open to allow penetration
of paint

3.2 Shelling

P3

Surface shall be free from visible shelling

3.3 Roll-overs/ roll
laminations/ cut laminations

P3

Surface shall be free from visible roll-overs/ laminations

3.4 Rolled-in extraneous

P3

Surface shall be free from rolled-in extraneous matter

3.5 Grooves and gouges

P2

The radius of grooves and gouges shall be not less than 2 mm

3.6 Indentations and roll

P2

Indentations and roll marks shall be smooth

2. Edges
2.1 Rolled edges

with a radius of not less than 2mm

shall be rounded

3. Surfaces generally

matter

Stand 2019-12

marks

For requirement P3 according to DIN EN ISO 8501-3, surfaces of hot-rolled steel products according to
DIN EN 10163-2, class B or better, do not have to be reworked, but shall fulfil at least the requirements of P2
regarding the feature 3.1 from Table IV.

19


DIN SPEC 18088-13:2019-12

11 Geometrical tolerances
11.2

Essential tolerances

11.2.2

Manufacturing tolerances

The following rules supplement the DIN EN 1090-2:2018-09, 11.2.2:
11.2.2.6

Welded Structural tubes

Tolerance class D on length requirements and class G on straightness according to DIN EN ISO 13920 are be
used for structural tubes, if no other requirements arise due to further processing or defined otherwise in

the component specification.
Out of roundness tolerances according to DIN EN 1090-2:2018-09, Table B.11, Criteria 1 are to be applied to
structural tubes wit r/t-ratio < 15 (> 3,2 % DCF)

Note
Component specification can establish higher requirements. The feasibility measuring horizontally
positioned thin walled tubes may be limited due to deformation under dead weight.
Requirements on Misalignment of plates according to DIN EN 1090-2:2018-09, Table B.11, Criteria 2 are not
valid. Maximum eccentricities are governed by fulfilment of misalignment requirement according to Table III
at both sides of the plates. Quality class A can be applied within the stability assessment according to
EN 1993-1-6, if the requirements according to Table III are complied.
11.2.2.9

Ring flanges

Manufacturing tolerances for ring flanges in accordance to Table V shall be complied after welding at shop
floor. Any deviating or additional requirements from design shall be respected in accordance to the
component specification.
Table V — Tolerances for ring flanges after welding at shop floor
Criteria

Accepted deviation

Flatness

max 2,0 mm by 360° und 1,0 mm by 30°

Flange thickness

—2,0/+3,0 mm

Wall thickness at neck

According to DIN EN 10029 class B by analogy

Outer and inner diameter

d —dyom ŠS +3 mm

Out ofroundness

đmax — đmịn Š 6mm

Pitch circle diameter each hole

địg — đạọm S+#1mm

Circumferential position of holes

<1mm

Diameter of holes
q

The accuracy of fit of
opposite sides of each
reserve of 0,5 mm for
agreed and used by all

20

— dom = 0/+0,5 mm

both parts of a flange pair shall be ensured. It shall be ensured that two holes on
other cover the bolt diameter even when the maximum tolerance is reached. A further
coating and thickness tolerances is recommended. A measurement procedure shall be
stakeholders. Reference planes and measuring tools shall be specified.


DIN SPEC 18088-13:2019-12

12 Inspection, testing and correction
12.4

Welding

12.4.1

General

The following rules supplement DIN EN 1090-2:2018-09, 12.4.1.
NDT personnel for VT (visual test) are also to be qualified according to DIN EN ISO 9712.
The NDT personnel are to demonstrate a Level 2 qualification for the respective procedure
DIN EN ISO 9712.
In addition, a NDT supervisor shall be appointed in accordance with
verify the NDT plans and confirms the correct performance of the tests.

12.4.2

DIN EN ISO 9712

according to

Level3

who

is to

Inspection after welding

12.4.2.1

Timing

DIN EN 1090-2:2018-09, Table 23 is replaced with the following table.
Minimum hold times shall be observed after completion of welding according to Table VI, before starting the
non-destructive testing.

Table VI — Minimum hold times
Hold time >
Plate thickness
mm

@
b

hours
S275 - S500

Above S500

Delivery conditions N and M

Delivery condition Q

t<25

Cooling period only

24

t>25

16

48

These values apply to the nominal parent material thickness ¢ of a full penetration weld. For different plate thicknesses the
greater thickness shall be applied. For individual partial penetration butt welds the governing criterion is the plate thickness,
but for pairs of partial penetration butt welds welded simultaneously it is the sum of the weld thicknesses s.
The time between weld completion and commencement of NDT shall be stated in the NDT report. In the case of “cooling period
only” this will last until the weld is cool enough for NDT to commence.

The following rules supplement DIN EN 1090-2:2018-09, 12.4.2.1:

Hold times may be further reduced if it has been shown that delayed cracking does not occur during the
process used.

If heat treatment or mechanical treatment are to be carried out, the NDT shall be performed after the heat

q

final treatment.

For welding performed offshore, minimum hold times shall be specified on a case-by-case basis.

21


DIN SPEC 18088-13:2019-12

12.4.2.3

Routine inspection and testing

The second paragraph in DIN EN 1090-2:2018-09, 12.4.3 is substituted by the following provisions:
For EXC1 and EXC2 welds, the extent of supplementary NDT shall be as specified in DIN EN 1090-2:2018-09,
Table 24. For EXC3 welds and higher, the scope of supplementary NDT shall be as in Table VII.
For EXC1 and EXC2 welds, plates with thicknesses smaller than 8 mm
defects.

do not need to be tested for inner

Table VII — Extent of routine supplementary NDT for EXC3 welds for offshore support structures
Type of weld

Scope of testing? for
particular inspection method

VT

MT(PT) |

UT

Tower
Butt welds at cans (circumferential and longitudinal welds)

100 %

20%

20%

Butt welds at flanges (circumferential welds)

100 %

20%

100 %

Full penetration welds (T-joint butt welds, e.g. trunnions, hoisting eyes)

100 %

20%

20%

Non full penetration welds (T-joint with fillet welds, doublings)

100 %

20%

—

Butt welds at cans (circumferential and longitudinal welds)

100 %

20%

100 %

Butt welds at flanges (circumferential welds)

100 %

100% | 100%

Full penetration welds (T-joint butt welds, e.g. trunnions, hoisting eyes)

100 %

100% | 100%

Non full penetration welds (T-joint with fillet welds, doublings)

100 %

100 %

—

Cans ofjacket tubes including piles

100 %

20%

100 %

'Welds in jacket structures

100 %

100%

| 100%

structural

100 %

10 %

10%

secondary structural

100 %

10%

—

Shear keys for grouted joints

100 %

20%

—

Surfaces after removal of assembling aids

100 %

100 %

—

Foundation structure

Full penetration welds, butt welds between
components at non dynamically loaded joints
Non full penetration welds, fillet welds between

components at non dynamically loaded joints

@

All welds that are not accessible during operation or which are only very hard to test shall be tested over their entire length
using an appropriate NDT method.

Key

Stand 2019-12

VT

MT
PT
UT

22

secondary

visual testing

magnetic particle testing
penetration testing
Ultrasonic testing


DIN SPEC 18088-13:2019-12

12.4.2.8

Alternative NDT-Methods

The following rules supplement DIN EN 1090-2:2018-09, 12.4.2:
Conventional ultrasonic testing (with a single transducer) can be replaced by phased array testing (UT PA) in
accordance with DIN EN ISO 13588 together with the time of flight diffraction method (UT TOFD) in

accordance with DIN EN ISO 10863.

If conventional ultrasonic testing is replaced as specified above, testing instructions are to be drawn
including at least the following information

up,

—

application limits in terms of weld geometry;

—

the minimum test categories and acceptance levels in accordance with the required quality level of
DIN EN ISO 5817.

Compliance with these requirements shall be ensured.
The results of phased array testing (UT PA) shall be related to the quality levels of DIN EN ISO 5817
accordance with DIN EN ISO 13588 together with DIN EN ISO 17640 and DIN EN ISO 11666.

in

The results of the time of flight diffraction method (UT TOFD) shall be related to the quality levels of
DIN EN ISO 5817 in accordance with DIN EN ISO 10863 together with DIN EN ISO 15626.
12.4.2.9

UT at tubular node connections for EXC3

The following rules supplement DIN EN 1090-2:2018-09, 12.4.2:
A test for UT testing is required prior to welding and the area to be scanned by the probe shall be marked on
each individual part after their assembly and prior to welding.
If there is a deviation from the requirements of Table A.5 as in DIN EN ISO 17640:2018-03 in the case of full
penetration welds at node connections due to limited access (e.g. when it is not possible to test the inside of
a flange), verifiability shall be proven using reference blocks and/or software modelling. The achievable
acceptance level is to be confirmed by the designer.

12.5

Mechanical fastening

12.5.2

Inspection and testing of preloaded bolted connections

12.5.2.9

Ring flange connections

The following rules apply in addition to DIN EN 1090-2:2018-09, 12.5.2:
Preloaded bolts with tightening in accordance with
connections in offshore foundation structures. The

Stand 2019-12

DIN EN 1993-1-8/NA for rotational
component specification.

tightening

DIN EN 1993-1-8 shall be used for ring flange
standard preloading force FpcŸ according to

techniques

is to be used

unless

otherwise

stated

in the

—

Once the production has been completed, the flatness deviations of the flanges according to Table V shall

—

The

be observed. In the assembled state, the area at the tower wall is decisive.
slope ag of the exterior flange surfaces

(Figure I) shall not exceed the limit value of 2%

after

preloading. Slopes greater than ag prior to preloading have no effect on fatigue damage as long as they
are reduced to a value below the limit value during the preloading process.

23


DIN SPEC 18088-13:2019-12

No more than 90 % of the standard preloading force F, ¢* shall be applied when verifying fatigue safety.
In principle, the preloading of the bolts is to be inspected and the bolts retightened, if necessary, during the
first six months after installation, but at the earliest after the number of operating hours specified in the

maintenance manual.

If the limit values for the flange gaps specified in the execution documents are not complied with,
appropriate measures shall be taken, such as filling the fatigue-relevant flange gaps with shims prior to

preloading, see 8.5.7 in this document.

NOTE __ All flange gaps k in the area of the tower wall (see Figure I) are relevant for the fatigue stress range of the
bolts, especially if they only extend over a part of the circumference, The influence on the fatigue damage increases as
the extension |, over the circumference decreases, meaning that the ratio of k/l is decisive.

a) L-Flange

b) T-Flange

Figure I — Imperfections in ring flange connections of tubular steel towers

q

24


DIN SPEC 18088-13:2019-12

Annex B
(normative)
Geometrical Tolerances

B.2 Manufacturing tolerances
In DIN EN 1090-2:2018-09, Table B.12 criterion no. 6 shall be substituted by the following:

oe

No

Criterion

Gap joints:

Parameter

A

——*†

A

l2

6

Gapg

bracing

{|

Functional Tolerances

Permitted

Permitted deviationA

Class 1
and Class 2

Class 1

Class 2

No requirement | A= +5 mm

A=+3mm

deviation A

between

components:
g>(' +t;+ 50)

\⁄⁄
/

Essential
Tolerances

where ¢; and £; are

the wall thicknesses

of braces

- Stand 2\

g

25