my @claim_records = ();
while (<CLAIMS>) {
    push(@claim_records, read_record($_));
}

##</code><code>##

## Put this at the top of your program
## This would be much longer in your program.
use constant CLAIM_TEMPLATE => 'A8A6A2';
use constant CLAIM_KEYS => qw(
    claim_batch_number
    claim_number
    claim_type
);

##</code><code>##

sub read_record {
    my ($line) = @_;

    my %claim_record = ();
    @claim_record{ CLAIM_KEYS } = unpack(CLAIM_TEMPLATE, $line);
    return \%claim_record;
}

##</code><code>##

my $sort_by = 'claim_type';
foreach $record ( sort sub { $a->{$sort_by} cmp $b->{$sort_by} } @claim_records ) {
     print STDOUT $record->{'claim_number'}, "\n";
}